Processes for the preparation of 2,5-furandicarboxylic acid and intermediates and derivatives thereof

ABSTRACT

The present disclosure provides processes for the production of 2-5-furandicarboxylic acid (FDCA) and intermediates thereof by the chemocatalytic conversion of a furanic oxidation substrate. The present disclosure further provides processes for preparing derivatives of FDCA and FDCA-based polymers. In addition, the present disclosure provides crystalline preparations of FDCA, as well as processes for making the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of, and claims thebenefit of priority to, U.S. Non-Provisional application Ser. No.16/552,096, filed Aug. 27, 2019, which is a continuation of and claimsthe benefit of priority to U.S. Non-Provisional application Ser. No.16/264,188, filed Jan. 31, 2019, now U.S. Pat. No. 10,442,780, which isa continuation of and claims the benefit of priority to U.S.Non-Provisional application Ser. No. 15/404,996, filed Jan. 12, 2017,now U.S. Pat. No. 10,208,006, and U.S. Provisional Application No.62/278,332, filed Jan. 13, 2016, whereby each of the aforementionedapplications is expressly incorporated by reference in its entirety.

FIELD

The present disclosure relates to novel processes for preparing2,5-furandicarboxylic acid pathway products, as well as related esters,amides, polymers, and compositions thereof.

BACKGROUND

Low cost, renewably-derived 2,5-furandicarboxylic acid (FDCA) and itsderivatives harbor considerable potential for commercial applications.See, e.g., “Top Value Added Chemicals from Biomass,” Volume I—Results ofScreening for Potential Candidates from Sugars and Synthesis Gas,produced by Staff at Pacific Northwest National Laboratory (PNNL),National Renewable Energy Laboratory (NREL), Office of Biomass Program(EERE); Eds. T. Werpy and G. Petersen (2003). In certain applications,they have the potential to displace aromatic dicarboxylic acids such asterephthalic and isophthalic acid. A. Corma, et al., Chem. Rev.,107:2411 (2007). FDCA and its derivatives are also useful in theproduction of other commodity chemicals. Id. For example, FDCA may behydrogenated to adipic acid, which is utilized in the production ofnylon. Id. Aromatic dicarboxylic acids are used for the production ofpolyesters and polyamides in the scale of tens of millions of tons peryear. See, e.g., “Modern Polyesters: Chemistry and Technology ofPolyesters and Copolyesters,” Eds. J. Scheirs and T. Long; Wiley (2013).

Methods of producing FDCA have been reported in the literature. Forexample, Corma, et al., report that FDCA can be produced by directoxidation of 5-hydroxymethylfurfural (HMF) with nitric acid, though withlow selectivity and yield. A. Corma, et al., supra. Verdeguer, et al.describe another process in which HMF is oxidized catalytically to FDCAusing 5% Pt supported on carbon in the presence of sodium or potassiumhydroxides with yields reported to be 70%. J. Mol. Catal. 85:327 (1993).They reported achieving FDCA yields of up to 80% using a 5% Pt/5% Pbcatalyst formulation on carbon in the presence of 1.25 M base solution.Id. When the amount of base was reduced to a concentration of 0.1 M, theauthors reported that no conversion of HMF to FDCA was achieved,suggesting high concentrations of base are an important requirement forachieving higher FDCA yields. See Id. In another reported method,Besson, et al., report that Pt/Bi catalysts supported on carbon canproduce FDCA with close to 100% selectivity under reaction conditions ofa high base (Na₂CO₃) to HMF ratio of 2 to 4. See WO 2014/122319. Anancillary result of adding a base (e.g., NaOH, KOH, Na₂CO₃) to thereaction is the formation of salts (e.g., sodium or potassium salts) ofFDCA. The formation of FDCA salts may be advantageous given that FDCAsalts are reported to be more water-soluble than FDCA itself, therebyaffording the potential opportunity to carry out the conversion processat higher HMF concentrations. Id. However, a disadvantage of such saltproduction is the need for further processing (e.g., further separationand/or conversion of the salt form of FDCA to FDCA) in the recovery ofFDCA.

U.S. Pat. No. 8,338,626 describes the production of FDCA and its estersby oxidation of mono- or dialkoxymethylfurfural in the presence of ahomogeneous catalytic system that is similar to the system used interephthalic acid production (Co/Mn/Br). The patent reports a maximumtotal yield of furandicarboxylics (with FDCA as a major constituent) of82%. Id. U.S. Pat. No. 7,700,788 describes a method of HMF oxidation toFDCA under high oxygen (air) pressure using a 5% Pt/ZrO₂ catalyst,prepared by a specific procedure from Pt acetylacetonate. In thisprocess, HMF at a concentration of three weight percent, in the presenceof base, and oxygen at a pressure of 150 psi resulted in the productionof FDCA at a yield of 90%.

U.S. Pat. No. 4,977,283 describes the oxidation of HMF at concentrationsaround 10% in a base-free solution of water and diethylene glycoldimethyl ether in the presence of a Pt (5%) on activated carboncatalyst. The process provided only low yields (8%) of FDCA with themajor product being 5-formylfuran-2-carboxylic acid.

In view of its potential as a biorenewable-derived replacement forpetroleum-derived compounds that are used in the production of plasticsand other materials, a commercially viable process for the production oflarge volumes of FDCA at high yields would be desirable.

SUMMARY

In one aspect, the present disclosure is directed to a process forproducing a 2,5-furandicarboxylic acid (FDCA) pathway product from afuranic oxidation substrate, the process comprising:

(a) contacting an oxidation feedstock comprising a furanic oxidationsubstrate and an oxidation solvent with oxygen in the presence of aheterogeneous oxidation catalyst under conditions sufficient to form areaction mixture for oxidizing the furanic oxidation substrate to anFDCA pathway product, and producing the FDCA pathway product,

wherein the oxidation solvent is a solvent selected from the groupconsisting of an organic solvent and a multi-component solvent,

wherein the reaction mixture is substantially free of added base,

wherein the heterogeneous oxidation catalyst comprises a solid supportand a noble metal, and

wherein the heterogeneous oxidation catalyst comprises a plurality ofpores and a specific surface area in the range of from 20 m²/g to 500m²/g. The noble metal can be platinum, gold, or a combination thereof.The oxidation solvent can be a multi-component solvent comprising waterand a water-miscible aprotic organic solvent. The water-miscible organicsolvent can be a water-miscible aprotic organic solvent. Thewater-miscible aprotic organic solvent can be selected from the groupconsisting of tetrahydrofuran, a glyme, dioxane, a dioxolane,dimethylformamide, dimethylsulfoxide, sulfolane, acetone,N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”), andgamma-valerolactone. The glyme can be selected from the group consistingof a monoglyme (1,2-dimethoxyethane), ethyl glyme, diglyme (diethyleneglycol dimethyl ether), ethyl diglyme, triglyme, butyl diglyme,tetraglyme, and a polyglyme. The water-miscible organic solvent can beselected from the group consisting of a light water-miscible organicsolvent and a heavy water-miscible organic solvent. The water and thewater-miscible organic solvent can be present in a ratio of from or anynumber in between 1:6 to 6:1 v/v water:water-miscible organic solvent.The water and the water-miscible organic solvent can be present in aratio of 1:1 v/v water:water-miscible organic solvent. Thewater-miscible organic solvent can be at least 10 vol % of themulti-component solvent.

The oxidation solvent can be a multi-component solvent comprising waterand two different water-miscible organic solvents. The water-miscibleorganic solvents both can be water-miscible aprotic organic solvents.Each of the water-miscible aprotic organic solvents can be independentlyselected from the group consisting of tetrahydrofuran, a glyme, dioxane,a dioxolane, dimethylformamide, dimethylsulfoxide, sulfolane, acetone,N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”), andgamma-valerolactone,

The furanic oxidation substrate can be 5-(hydroxymethyl)furfural (HMF).The furanic oxidation substrate can be selected from the groupconsisting of diformylfuran (DFF), hydroxymethylfurancarboxylic acid(HMFCA), and formylfurancarboxylic acid (FFCA).

The oxidation feedstock can include the furanic oxidation substrate at aconcentration of at least 5% by weight. The furanic oxidation substratecan be present in the oxidation feedstock at a concentration of at least10% by weight.

The heterogeneous oxidation catalyst can comprise the metal at a loadingin the range of from or any number in between 0.3% to 5% by weight ofthe heterogeneous oxidation catalyst. The heterogeneous oxidationcatalyst can further comprise a promoter.

The solid support can comprise a material selected from the groupconsisting of a metal oxide, a carbonaceous material, a polymer, a metalsilicate, a metal carbide, and any combination of two or more thereof.The metal oxide can be selected from the group consisting of silica,zirconia, and alumina. The carbonaceous material can be carbon black.The solid support can be a composite material comprising a binder and amaterial selected from the group consisting of a metal oxide, acarbonaceous material, a polymer, a metal silicate, and a metal carbide.

The heterogeneous oxidation catalyst can comprise a specific surfacearea in the range of from or any number in between 25 m²/g to 350 m²/g,from or any number in between 25 m²/g to 250 m²/g, from or any number inbetween 25 m²/g to 225 m²/g, from or any number in between 25 m²/g to200 m²/g, from or any number in between 25 m²/g to 175 m²/g, from or anynumber in between 25 m²/g to 150 m²/g, from or any number in between 25m²/g to 125 m²/g, or from or any number in between 25 m²/g to 100 m²/g.The heterogeneous oxidation catalyst can comprise a pore volume whereinat least 50% of the pore volume is from pores having a pore diameter inthe range of from or any number in between 5 nm to 100 nm. Theheterogeneous oxidation catalyst can comprise a pore volume wherein nomore than 10% of the pore volume of the heterogeneous oxidation catalystis from pores having a pore diameter less than 10 nm but not zero. Theheterogeneous oxidation catalyst can comprise a pore volume where nomore than 10% of the pore volume of the heterogeneous oxidation catalystis from pores having a pore diameter ranging from or any number inbetween 0.1 nm to 10 nm. The heterogeneous oxidation catalyst cancomprise a pore volume where no more than 5% of the pore volume of theheterogeneous oxidation catalyst is from pores having a pore diameterless than 10 nm but not zero. The pore volume of the heterogeneousoxidation catalyst can be no more than 5% of the pores having a porediameter ranging from or any number in between 0.1 nm to 10 nm. The porevolume of the heterogeneous oxidation catalyst can be no more than 2.5%of the pores having a pore diameter less than 10 nm but not zero. Thepore volume of the heterogeneous oxidation catalyst can be no more than2.5% of the pores having a pore diameter ranging from or any number inbetween 0.1 nm to 10 nm. The plurality of pores can be characterized bya mean pore diameter in the range of from or any number in between 10 nmto 100 nm.

The heterogeneous oxidation catalyst can comprise a second plurality ofpores, where at least one of the first or second pluralities of pores ischaracterized by a mean pore diameter in the range of from or any numberin between 10 nm to 100 nm. Each of the first and second plurality ofpores can be characterized by a mean pore diameter in the range of fromor any number in between 10 nm to 100 nm.

The heterogeneous oxidation catalyst can comprise a specific pore volumethat is in the range of from or any number in between 0.1 cm³/g to 1.5cm³/g.

The oxygen can be present at a molar ratio of oxygen:furanic oxidationsubstrate in the range of from or any number in between 2:1 to 10:1. Themolar ratio of oxygen:furanic oxidation substrate can be in the range offrom or any number in between 2:1 to 5:1. The oxygen can be present at apressure (p_(O2)) in the range of from or any number in between 50 psigto 1000 psig. The oxygen can be present at a pressure (p_(O2)) in therange of from or any number in between 50 psig to 200 psig.

The contacting step can be carried out at a temperature in the range offrom or any number in between 50° C. to 200° C., in the range of from orany number in between 80° C. to 180° C., or in the range of from or anynumber in between 100° C. to 160° C. The FDCA pathway product can beproduced at a yield of at least 80%. The FDCA pathway product can beproduced at a selectivity of at least 90%. The contacting step can becarried out for a time sufficient to produce a product solutioncomprising the oxidation solvent and the FDCA pathway product at aconcentration of at least 5% by weight. The contacting step can producea product solution comprising the oxidation solvent and the FDCA pathwayproduct at a concentration of at least 5% by weight.

The process can comprise a second oxidation step, wherein the secondoxidation step comprises:

(b) contacting a second oxidation feedstock comprising a second furanicoxidation substrate and a second oxidation solvent with oxygen in thepresence of a second heterogeneous oxidation catalyst under conditionssufficient to form a second reaction mixture for oxidizing the secondfuranic oxidation substrate to produce a second FDCA pathway product,and producing the second FDCA pathway product,

wherein (the first) contacting step (a) produces a first FDCA pathwayproduct that is an FDCA pathway intermediate compound, either alone ortogether with FDCA,

wherein the second furanic oxidation substrate is the first FDCA pathwayproduct,

wherein the second reaction mixture is substantially free of added base,and

-   -   wherein the second heterogeneous oxidation catalyst comprises a        second solid support and a second noble metal, that may be the        same or different from the (first) noble metal in step (a), and

wherein the second heterogeneous oxidation catalyst comprises aplurality of pores and a specific surface area in the range of from orany number in between 20 m²/g to 500 m²/g.

The second noble metal can be selected from the group consisting ofplatinum, gold, and a combination thereof. The second heterogeneousoxidation catalyst can be the same as the (first) heterogeneousoxidation catalyst of step (a). The second heterogeneous oxidationcatalyst can be different from the (first) heterogeneous oxidationcatalyst of step (a). The second heterogeneous oxidation catalyst cancomprise a second metal that is not the same as the (first) metal in the(first) heterogeneous oxidation catalyst of step (a). The (first)oxidation solvent in step (a) can be the same as the second oxidationsolvent in step (b).

The process may recover the FDCA pathway product from the oxidationsolvent in step (a). The process may recover the second FDCA pathwayproduct from the second oxidation solvent in step (b). The process mayinvolve purifying the FDCA pathway product from step (a). The processmay involve purifying the second FDCA pathway product from step (b). Thepurifying step can comprise a crystallization process. Thecrystallization process can comprise providing a crystallizationsolution comprising the FDCA pathway product and a crystallizationsolvent at a first temperature in the range of from or any number inbetween 50° C. to 220° C., and cooling the crystallization solution to asecond temperature that is lower than the first temperature to form aplurality of FDCA pathway product crystals of different particle sizes.The crystallization solvent can be the (first) oxidation solvent in step(a). The crystallization process can comprises providing acrystallization solution comprising the second FDCA pathway product anda crystallization solvent at a first temperature in the range of from orany number in between 50° C. to 220° C., and cooling the crystallizationsolution to a second temperature that is lower than the firsttemperature to form a plurality of second FDCA pathway product crystalsof different particle sizes. The crystallization solvent can be selectedfrom the group consisting of the first oxidation solvent of step (a) andthe second oxidation solvent of step (b).

The process can include a crystallization process that comprisesproviding a first crystallization solution comprising the FDCA pathwayproduct and a first crystallization solvent selected from the groupconsisting of water, an organic solvent, and combinations thereof; andremoving a first portion of the first crystallization solvent from thefirst crystallization solution to produce a first FDCA pathway productslurry, wherein the first FDCA pathway product slurry comprises a firstplurality of FDCA pathway product crystals of different particle sizesand a second portion of the first crystallization solvent. Thecrystallization process can further include dissolving the firstplurality of FDCA pathway product crystals in a second crystallizationsolvent to produce a second crystallization solution comprising the FDCApathway product and the second crystallization solvent; removing a firstportion of the second crystallization solvent from the secondcrystallization solution to produce a second FDCA pathway product slurrycomprising a second plurality of FDCA pathway product crystals ofdifferent particle sizes and a second portion of the secondcrystallization solvent; and separating the second plurality of FDCApathway product crystals from the second portion of the secondcrystallization solvent.

The process can include a crystallization process that comprisesproviding a first crystallization solution comprising the second FDCApathway product and a first crystallization solvent selected from thegroup consisting of water, an organic solvent, and combinations thereof;and removing a first portion of the first crystallization solvent fromthe first solution to produce a first FDCA pathway product slurry,wherein the first FDCA pathway product slurry comprises a firstplurality of second FDCA pathway product crystals of different particlesizes and a second portion of the first crystallization solvent; andoptionally separating the first plurality of second FDCA pathway productcrystals from the second portion of the first crystallization solvent.The crystallization process can further include dissolving the firstplurality of second FDCA pathway product crystals in a secondcrystallization solvent to produce a second crystallization solutioncomprising the second FDCA pathway product and the secondcrystallization solvent; removing a first portion of the secondcrystallization solvent from the second crystallization solution toproduce a second FDCA pathway product slurry comprising a secondplurality of the second FDCA pathway product crystals of differentparticle sizes and a second portion of the second crystallizationsolvent; and separating the second plurality of the second FDCA pathwayproduct crystals from the second portion of the second crystallizationsolvent.

The process can further comprise converting FDCA to an ester of FDCA bycontacting the FDCA with an alcohol under conditions sufficient toproduce a corresponding ester of FDCA. The alcohol can be an aliphaticalcohol, a diol, ethylene glycol, or an aromatic alcohol. The ester ofFDCA can be a diester of FDCA. The alcohol can be methanol and thediester of FDCA can be the dimethyl ester of FDCA. The process canfurther comprise converting FDCA or an FDCA ester to an FDCA amide bycontacting the FDCA or FDCA ester with an amino-substituted compoundunder conditions sufficient to produce a corresponding FDCA amide. Theamino-substituted compound can be 1,6-hexamethylenediamine. The FDCAamide can be an FDCA diamide. The process can further compriseconverting FDCA to an FDCA halide by contacting the FDCA with ahydrohalic acid having the formula HX, wherein X is a halide, underconditions sufficient to produce the corresponding FDCA halide. Thehalide can be chloride and the FDCA halide can be FDCA chloride. TheFDCA chloride can be FDCA dichloride.

The process can further comprise polymerizing FDCA or derivative thereofunder conditions sufficient to produce an FDCA-based polymer. The FDCAderivative can be selected from the group consisting of an FDCA diester,an FDCA dihalide, and an FDCA diamide. The FDCA diester can be dimethylFDCA ester. The FDCA diester can be di(ethylene glycol) FDCA ester. Thepolymerizing step can be a polycondensation reaction. The process cancomprise a transesterification reaction that precedes thepolycondensation reaction. The polymerizing step can comprise contactingthe FDCA derivative with a second monomer. The second monomer can be apolyol.

The process can further comprise:

(a^(o)) prior to step (a), contacting a carbohydrate feedstockcomprising a sugar and a dehydration solvent with a catalyst underconditions sufficient to form a reaction mixture for dehydrating thesugar to produce the furanic oxidation substrate, wherein the furanicoxidation substrate is present in a dehydration product solution thatcomprises the furanic oxidation substrate and the dehydration solvent.

The sugar can be fructose and the furanic oxidation substrate can beHMF. The oxidation feedstock of step (a) can comprise the dehydrationproduct solution of step (a^(o)). With respect to the (first)heterogeneous oxidation catalyst, (1) the noble metal can be platinum;(2) the solid support can be selected from the group consisting ofsilica and a carbonaceous material; and (3) the plurality of pores canbe characterized by a mean pore diameter in the range of from or anynumber in between 10 nm to 100 nm. With respect to the (second)heterogeneous oxidation catalyst: (1) the noble metal can be platinum;(2) the solid support can be selected from the group consisting ofsilica and a carbonaceous material; and (3) the plurality of pores canbe characterized by a mean pore diameter in the range of from or anynumber in between 10 nm to 100 nm.

In another aspect, the present disclosure is directed to a process forproducing a crystalline FDCA pathway product composition, the methodcomprising:

providing a crystallization solution comprising an FDCA pathway productand a crystallization solvent that is a multi-component solventcomprising water and a water-miscible organic solvent;

initiating crystallization of the FDCA pathway product; and

producing a plurality of FDCA pathway product crystals of differentparticle sizes. In certain embodiments, the water-miscible organicsolvent is a water-miscible aprotic organic solvent.

The water-miscible organic solvent can be a water-miscible aproticorganic solvent. The water-miscible aprotic organic solvent can beselected from the group consisting of tetrahydrofuran, a glyme, dioxane,a dioxolane, dimethylformamide, dimethylsulfoxide, sulfolane, acetone,N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”), andgamma-valerolactone. The water-miscible organic solvent can be selectedfrom the group consisting of a light water-miscible organic solvent anda heavy water-miscible organic solvent.

The multi-component solvent can comprise the water and thewater-miscible organic solvent in a ratio of from or any number inbetween 1:6 to 6:1 v/v. The multi-component solvent can comprise thewater and the water-miscible organic solvent in a ratio within a rangedefined by 1:6 to 6:1 v/v. The multi-component solvent can comprise atleast 10 vol % water-miscible organic solvent.

The crystallization can be initiated by cooling the crystallizationsolution to a temperature below 60° C. The crystallization can beinitiated by cooling the crystallization solution to a temperature below50° C. The crystallization can be initiated by removing a portion of thecrystallization solvent to produce a first FDCA pathway product slurry,wherein the first FDCA pathway product slurry comprises a firstplurality of FDCA pathway product crystals and a second portion ofcrystallization solvent or component thereof. The seed crystals can beadded to the crystallization solution.

The plurality of FDCA pathway product crystals can be characterized by amedian (D50) particle size in the range of from or any number in between50 μm to 5000 μm or in the range of from or any number in between 50 μmto 2000 μm. The plurality of FDCA pathway product crystals can becharacterized by a median (D50) particle size in the range of from orany number in between 150 μm to 750 μm.

The process for producing a crystalline FDCA pathway product compositioncan further comprise dissolving the first plurality of FDCA pathwayproduct crystals in a second crystallization solvent to produce a secondcrystallization solution comprising a second plurality of FDCA pathwayproduct crystals and a second crystallization solvent; removing a firstportion of the second crystallization solvent from the secondcrystallization solution to produce a second FDCA pathway product slurrythat comprises a second plurality of FDCA crystals and a second portionof the second crystallization solvent; and separating the secondplurality of FDCA pathway product crystals from the second portion ofthe second crystallization solvent. Seed crystals can be added to thesecond crystallization solution. The dissolving step can be carried outat a temperature in the range of from or any number in between 80° C. to220° C., or in the range of from or any number in between 60° C. to 180°C., or in the range of from or any number in between 80° C. to 150° C.In a still further aspect, the present disclosure is directed to acrystalline FDCA composition wherein the composition comprises aplurality of FDCA crystal particles of different particles sizes,wherein the plurality is characterized by a median particle size (D50)in the range of from 50 μm to 5000 μm, such as 50, 75, 100, 200, 300,400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 4000,4500, or 5000 μm or within a range defined by any two of theaforementioned sizes.

In another aspect, the present disclosure is directed to a process forconverting FDCA to an FDCA derivative selected from the group consistingof an FDCA salt, an FDCA ester, an FDCA amide, and an FDCA halide.

In a still further aspect, the present disclosure is directed to processfor producing an FDCA-based polymer selected from the group consistingof an FDCA-based polyester and an FDCA-based polyamide.

In some embodiments, the present disclosure is directed to a compositioncomprising: (a) an oxidation feedstock comprising a furanic oxidationsubstrate and an oxidation solvent; (b) oxygen; (c) a heterogeneousoxidation catalyst; (d) an FDCA pathway product; wherein the oxidationsolvent is a solvent selected from the group consisting of an organicsolvent and a multi-component solvent; wherein the heterogeneousoxidation catalyst comprises a solid support and a noble metal; whereinthe heterogeneous oxidation catalyst comprises a plurality of pores anda specific surface area in the range of from or any number in between 20m²/g to 500 m²/g; and wherein the composition is substantially free ofadded base.

The noble metal can be selected from the group consisting of platinum,gold, and a combination thereof. The oxidation solvent can be amulti-component solvent comprising water and a water-miscible organicsolvent. The water-miscible organic solvent can be a water-miscibleaprotic organic solvent. The water-miscible aprotic organic solvent canbe selected from the group consisting of tetrahydrofuran, a glyme,dioxane, a dioxolane, dimethylformamide, dimethylsulfoxide, sulfolane,acetone, N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”),and gamma-valerolactone. The water-miscible organic solvent can beselected from the group consisting of a light water-miscible organicsolvent and a heavy water-miscible organic solvent.

The water and the water-miscible organic solvent can be present in aratio of from or any number in between 1:6 to 6:1 v/vwater:water-miscible organic solvent. The water and the water-miscibleorganic solvent can be present in a ratio within a range defined by 1:6to 6:1 v/v water:water-miscible organic solvent. The water and thewater-miscible organic solvent can be present in a ratio of 1:1 v/vwater:water-miscible organic solvent. The water-miscible organic solventcan comprise at least 10 vol % of the multi-component solvent.

The furanic oxidation substrate can be 5-(hydroxymethyl)furfural (HMF).The furanic oxidation substrate can be selected from the groupconsisting of diformylfuran (DFF), hydroxymethylfurancarboxylic acid(HMFCA), and formylfurancarboxylic acid (FFCA).

The oxidation feedstock can comprise the furanic oxidation substrate ata concentration of at least 5% by weight. The furanic oxidationsubstrate can be present in the oxidation feedstock at a concentrationof at least 10% by weight.

The heterogeneous oxidation catalyst can comprise the metal at a loadingin the range of from or any number in between 0.3% to 5% by weight ofthe heterogeneous oxidation catalyst. The heterogeneous oxidationcatalyst can further comprise a promoter.

The solid support can comprise a material selected from the groupconsisting of a metal oxide, a carbonaceous material, a polymer, a metalsilicate, a metal carbide, and any combination of two or more thereof.The metal oxide can be selected from the group consisting of silica,zirconia, and alumina. The carbonaceous material can be carbon black.The solid support can be a composite material comprising a binder and amaterial selected from the group consisting of a metal oxide, acarbonaceous material, a polymer, a metal silicate, and a metal carbide.

The heterogeneous oxidation catalyst can comprise a specific surfacearea in the range of from or any number in between 25 m²/g to 350 m²/g,from or any number in between 25 m²/g to 250 m²/g, from or any number inbetween 25 m²/g to 225 m²/g, from or any number in between 25 m²/g to200 m²/g, from or any number in between 25 m²/g to 175 m²/g, from or anynumber in between 25 m²/g to 150 m²/g, from or any number in between 25m²/g to 125 m²/g, or from or any number in between 25 m²/g to 100 m²/g.The heterogeneous oxidation catalyst can comprise a pore volume whereinat least 50% of the pore volume is from pores having a pore diameter inthe range of from or any number in between 5 nm to 100 nm. Theheterogeneous oxidation catalyst can comprise a pore volume wherein nomore than 10% of the pore volume of the heterogeneous oxidation catalystis from pores having a pore diameter less than 10 nm. The heterogeneousoxidation catalyst can comprise a pore volume wherein no more than 10%of the pore volume of the heterogeneous oxidation catalyst is from poreshaving a pore diameter ranging from or any number in between 0.1 nm to10 nm. The pore volume of the heterogeneous oxidation catalyst can be nomore than 2.5% of the pores having a pore diameter less than 10 nm butnot zero. The pore volume of the heterogeneous oxidation catalyst can beno more than 2.5% of the pores having a pore diameter ranging from orany number in between 0.1 nm to 10 nm. The plurality of pores can becharacterized by a mean pore diameter in the range of from or any numberin between 10 nm to 100 nm. The heterogeneous oxidation catalyst cancomprise a specific pore volume that is in the range of from or anynumber in between 0.1 cm³/g to 1.5 cm³/g.

The heterogeneous oxidation catalyst can comprise a second plurality ofpores, wherein at least one of the first or second pluralities of poresis characterized by a mean pore diameter in the range of from or anynumber in between 10 nm to 100 nm. Each of the first and secondplurality of pores can be characterized by a mean pore diameter in therange of from or any number in between 10 nm to 100 nm.

The oxygen can be present at a molar ratio of oxygen:furanic oxidationsubstrate in the range of from or any number in between 2:1 to 10:1. Themolar ratio of oxygen:furanic oxidation substrate can be in the range offrom or any number in between 2:1 to 5:1. The oxygen can be present at apressure (p_(O2)) in the range of from or any number in between 50 psigto 1000 psig. The oxygen can be present at a pressure (p_(O2)) in therange of from or any number in between 50 psig to 200 psig.

In some embodiments, the present disclosure is directed to an apparatuscomprising: (a) an oxidation reaction zone; (b) an oxygen feed streamcomprising oxygen; (c) an oxidation feedstock stream comprising afuranic oxidation substrate and an oxidation solvent; wherein theoxidation solvent is a solvent selected from the group consisting of anorganic solvent and a multi-component solvent; (d) a pathway productstream comprising an FDCA pathway product; wherein the oxygen feedstream and oxidation feedstock stream are passed into the oxidationreaction zone and react to produce an FDCA pathway product; wherein theoxidation reaction zone contains a heterogeneous oxidation catalyst,oxygen, a furanic oxidation substrate, and an oxidation solvent; whereinthe FDCA pathway product stream exits the oxidation reaction zone;wherein the heterogeneous oxidation catalyst comprises a solid supportand a noble metal; wherein the heterogeneous oxidation catalystcomprises a plurality of pores and a specific surface area in the rangeof from or any number in between 20 m²/g to 500 m²/g; wherein theoxidation reaction zone is substantially free of added base.

The apparatus can further comprise a recycle stream wherein the recyclestream comprises unreacted furanic oxidation substrate; wherein therecycle stream exits the oxidation reaction zone; and wherein theapparatus contains a means for optionally passing the recycle streamback into the oxidation reaction zone.

The apparatus can further comprise (e) a second oxidation reaction zone;(f) a second oxygen feed stream comprising oxygen; (g) a second pathwayproduct stream comprising an FDCA pathway product; wherein the pathwayproduct stream from element (d) and the second oxygen feed stream arepassed into the second oxidation reaction zone and react to produce anFDCA pathway product; wherein the second pathway product stream exitsthe second oxidation reaction zone; wherein the second oxidationreaction zone contains a second heterogeneous oxidation catalyst,oxygen, and the pathway product stream from element (d); wherein thesecond heterogeneous oxidation catalyst comprises a solid support and anoble metal; wherein the second heterogeneous oxidation catalystcomprises a plurality of pores and a specific surface area in the rangeof from or any number in between 20 m²/g to 500 m²/g; wherein the secondoxidation reaction zone is substantially free of added base. Theapparatus can further comprise a recycle stream wherein the recyclestream comprises unreacted pathway product stream from element (d);wherein the recycle stream exits the second oxidation reaction zone; andwherein the apparatus contains a means for optionally passing therecycle stream into the oxidation reaction zone from element (a).

In some embodiments, the present disclosure is directed to a process forproducing a furanic oxidation substrate, the process comprisingcontacting a carbohydrate feedstock comprising a sugar and a dehydrationsolvent with an acid catalyst under conditions sufficient to form adehydration reaction mixture for dehydrating the sugar to produce afuranic oxidation substrate, wherein the acid catalyst is an acidselected from the group consisting of HBr, H₂SO₄, HNO₃, HCl, HI, H₃PO₄,triflic acid, methansulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid, wherein when the acid catalyst is not HBr, thedehydration reaction mixture further comprises a bromide salt, andwherein the dehydration solvent comprises N-methyl-pyrrolidone (NMP).

The acid catalyst can be HBr. The acid catalyst can be selected from thegroup consisting of H₂SO₄, HNO₃, HCl, HI, H₃PO₄, triflic acid,methansulfonic acid, benzenesulfonic acid, and p-toluene sulfonic acid,and wherein the dehydration reaction mixture comprises a bromide salt.The bromide salt can be selected from the group consisting of LiBr,NaBr, KBr, MgBr₂, CaBr₂, ZnBr₂, tetramethylammonium bromide,tetraethylammonium bromide, tetrapropylammonium bromide,tetrabutylammonium bromide, and any combination of two or more thereof.The acid catalyst can further comprise a Lewis acid. The Lewis acid canbe selected from the group consisting of a borontrihalide, anorganoborane, an aluminum trihalide, a phosphorus pentafluoride, anantimony pentafluoride, a rare earth metal triflate, a metal halide, ametal trifluoroacetate, or a metal cation ether complex. The Lewis acidcan be a metal halide. The metal halide can be ZnCl₂ or ZnBr₂.

The yield of furanic oxidation substrate can be at least 60%, or atleast 70%, or at least 80%, or at least 90% or at least 95%, or at least98% or at least 99%. The sugar can be fructose. The furanic oxidationsubstrate can be HMF.

The dehydration reaction mixture can be maintained at a temperature inthe range of from or any number in between 80° C. and 160° C., or 80° C.and 150° C., or 80° C. and 140° C., or 80° C. and 130° C., or 80° C. and120° C., or 80° C. and 110° C., or 80° C. and 100° C.

The dehydration solvent can further comprise water. The dehydrationsolvent can comprise water and NMP in a range from or any number inbetween 1-5 wt % water and 99-95% NMP, or 5-10 wt % water and 95-90 wt %NMP, or 10-15 wt % water and 90-85 wt % NMP, or 15-20 wt % water and85-80 wt % NMP, or 20-25 wt % water and 80-75 wt % NMP, or 25-30 wt %water and 75-70 wt % NMP, or 30-35 wt % water and 70-65 wt % NMP, or35-40 wt % water and 65-60 wt % NMP, or 40-45 wt % water and 60-55 wt %NMP, or 45-50 wt % water and 55-50 wt % NMP, or 50-55 wt % water and50-45 wt % NMP, or 55-60 wt % water and 45-40 wt % NMP, or 60-65 wt %water and 40-35 wt % NMP, or 65-70 wt % water and 35-30 wt % NMP, or70-75 wt % water and 30-25 wt % NMP, or 75-80 wt % water and 25-20 wt %NMP, or 80-85 wt % water and 20-15 wt % NMP, or 85-90 wt % water and15-10 wt % NMP, or 90-95 wt % water and 10-5 wt % NMP, or 95-99 wt %water and 5-1 wt % NMP.

The dehydration solvent can further comprise a second organic solventspecies. The second organic solvent species can be a water-miscibleorganic solvent that is not N-methyl-pyrrolidone (NMP). Each of thewater-miscible aprotic organic solvent can be selected from the groupconsisting of tetrahydrofuran, a glyme, dioxane, a dioxolane,dimethylformamide, dimethylsulfoxide, sulfolane, acetone, methyl ethylketone (“MEK”), and gamma-valerolactone, The furanic oxidation substratecan be present in a dehydration product solution that comprises thefuranic oxidation substrate and the dehydration solvent. The dehydrationproduct solution further can comprise an unreacted sugar. Thedehydration product solution can be a mixture that includes humins. Thedehydration product solution or the mixture that includes humins can besubjected to one or more membranes to effect separation of the furanicoxidation substrate from one or more components selected from the groupconsisting of a humin, an unreacted sugar, or a combination thereof. Theone or more membranes can be selected from the group consisting of anultrafiltration, a nanofiltration membrane, and a combination thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts the net conversion of 5-(hydroxymethyl)furfural (HMF) (I)to 2,5-furandicarboxylic acid (FDCA) (V).

FIG. 2 depicts potential FDCA pathway intermediates that may begenerated by the oxidation of HMF. These intermediates are diformylfuran(II), hydroxymethylfurancarboxylic acid (III), and formylfurancarboxylicacid (IV). The final oxidation product in the pathway is FDCA (V).

FIG. 3 depicts the solubility of FDCA (weight percent) in H₂O (▴),dioxane (♦), diglyme (▪), 1:1 v/v diglyme:H₂O (∘), and 4:1 v/vdioxane:H₂O (•) at temperatures in the range of from 22° C. to 140° C.

FIG. 4 is a schematic of a single oxidation reaction zone process forconverting a furanic oxidation substrate to a desired FDCA pathwayproduct.

FIG. 5 is a schematic of an integrated multi-oxidation reaction zoneprocess for converting a furanic oxidation substrate to a desired FDCApathway product.

FIG. 6 depicts an integrated crystallization process for producingrefined crystalline FDCA product from a feedstock that is the productstream of an oxidation reaction zone. The oxidation reaction zoneproduct stream comprises FDCA and a multi-component solvent of water anda water-miscible light organic solvent. The process utilizes a solventswitch from the co-solvent to water between the first and secondcrystallization steps.

FIG. 7 depicts an integrated crystallization process for producingrefined crystalline FDCA from a feedstock that is the product stream ofan oxidation reaction zone. The process utilizes a multi-componentsolvent comprising water and a water-miscible light organic solvent.

FIG. 8 depicts an integrated crystallization process for producingrefined crystalline FDCA from a feedstock that is the product stream ofan oxidation reaction zone. The oxidation reaction zone product streamcomprises FDCA and a co-solvent of water and a water-miscible heavyorganic solvent. The process utilizes a solvent switch from theco-solvent to water between the first and second crystallization steps.

FIG. 9 depicts an integrated crystallization process for producingrefined crystalline FDCA from a feedstock that is the product stream ofan oxidation reaction zone. The oxidation reaction zone product streamcomprises FDCA and a multi-component solvent of water and awater-miscible heavy organic solvent.

FIG. 10 depicts an integrated process for producing a purifieddimethylester of FDCA by distillation.

FIG. 11 depicts an integrated process for producing a purifieddimethylester of FDCA by crystallization.

FIG. 12 depicts the temperature dependence of FDCA solubility inDioxane/H₂O solvent compositions.

FIG. 13 depicts the temperature dependence of FDCA solubility in DME/H₂Osolvent compositions.

FIG. 14 depicts a plot of percent HMF yield versus percent conversionfor the conversion of fructose to HMF using HBr and H₂SO₄ in NMP andH₂O.

FIG. 15 depicts a plot of percent HMF yield versus percent conversionfor the conversion of fructose to HMF using HBr and HCl in NMP and H₂O.

FIG. 16 depicts a plot of percent HMF yield versus percent conversionfor the conversion of fructose to HMF using HBr in NMP and H₂O.

DETAILED DESCRIPTION I. Processes for Producing FDCA Pathway Products

In one embodiment, the present disclosure provides novel processes forproducing desired furandicarboxylic acid (FDCA) pathway products at highyields and high selectivities from the oxidation of a furanic oxidationsubstrate. Significantly, these results are achieved without the needfor any added base. The base-free (and substantially base-free)oxidative processes of the present disclosure are attractive as comparedto existing processes for producing FDCA and related pathway productsbecause, inter alia, they do not require further downstream processingto remove added base, or any by-products generated as a result of thebase addition. As used herein, the terms “furandicarboxylic acid pathwayproduct” and “FDCA pathway product” are used interchangeably herein torefer to 2,5-furandicarboxylic acid (FDCA) or a 2,5-furandicarboxylicacid pathway intermediate compound. The net conversion of HMF to FDCA isshown in FIG. 1. The term “furandicarboxylic acid pathway” is usedherein to refer to the pathway depicted in FIG. 2. As used herein, theterms “2,5-furandicarboxylic acid pathway intermediate compound” and“FDCA pathway intermediate compound” are used interchangeably to referto any one of diformylfuran (DFF), hydroxymethylfurancarboxylic acid(HMFCA), and 5-formylfurancarboxylic acid (FFCA), which correspond tocompounds II, III, and IV in FIG. 2, respectively.

More specifically, the present disclosure provides a process forproducing an FDCA pathway product from a furanic oxidation substrate,the process comprising:

(a) contacting an oxidation feedstock comprising a furanic oxidationsubstrate and an oxidation solvent with oxygen in the presence of aheterogeneous oxidation catalyst under conditions sufficient to form areaction mixture for oxidizing the furanic oxidation substrate to anFDCA pathway product, and producing the FDCA pathway product,

wherein the oxidation solvent is a solvent selected from the groupconsisting of an organic solvent and a multi-component solvent, whereinthe reaction mixture is substantially free of added base, and whereinthe heterogeneous oxidation catalyst comprises a solid support and anoble metal, and

wherein the heterogeneous oxidation catalyst comprises a plurality ofpores and a specific surface area in the range of from or any number inbetween 20 m²/g to 500 m²/g, such as e.g., 20, 30, 40, 50, 60, 70, 80,90, 100, 120, 140, 160, 180, 200, 225, 250, 275, 300, 325, 350, 375,400, 425, 450, 475, or 500 m²/g or is within a range defined by any twoof the aforementioned surface areas.

The term “substantially free of added base” is used herein to refer tothe lack of any base added to the reaction mixture (i.e., no addedbase), or the addition of a de minimis quantity of base. The term “deminimis quantity of base” refers herein to an amount of base which, whenadded to a reaction mixture employed in the practice of the presentdisclosure, does not alter the oxidation reaction by more than 1% withrespect to product yield or product selectivity, as compared to the sameoxidation reaction performed under the same conditions with theexception that no base is added to the reaction mixture. Typically, theprocesses of the present disclosure are carried out under base-freeconditions, i.e., no base is added to the reaction mixture during thecontacting (i.e., oxidation) step.

Oxidation processes of the present disclosure result in the productionof the desired FDCA pathway product at a yield that is typically atleast 80% and a selectivity that is typically at least 90% (both on amolar basis). In some embodiments, the yield is at least 85%, and inother embodiments, it is at least 90%, at least 95%, and often, at least98% or at least 99%. In some embodiments, the yield ranges from between85-90%, 87-92%, 90-95%, 92-97%, 95-98%, or 97-99%, or is within a rangedefined by any of two of the aforementioned percentages. The selectivitywith respect to production of the desired FDCA pathway product is moretypically at least 91% or at least 92% or at least 93% or at least 94%or at least 95% or at least 96% or at least 97% or at least 98% or atleast 99%. In some embodiments, the selectivity with respect to thedesired FDCA pathway product ranges from between 91-93%, 92-94%, 93-95%,94-96%, 95-97%, 96-98%, 97-99%, or is within a range defined by any oftwo of the aforementioned percentages. The desired FDCA pathway productis usually FDCA.

The term “oxidation feedstock” refers herein to a source material forthe furanic oxidation substrate. As used herein, the term “furanicoxidation substrate” refers to a compound that is HMF or an FDCAintermediate compound (i.e., DFF, HMFCA, FFCA, or combination thereof)or a combination thereof. Oxidation feedstocks employed in the practiceof the processes described herein may be employed in any of a variety offorms, including, for example, a solution, a suspension, a dispersion,an emulsion, and the like. Typically, the oxidation feedstock comprisesthe furanic oxidation substrate in solution with the oxidation solvent.

In the oxidation processes described herein, the FDCA pathway product istypically FDCA. In certain embodiments, the furanic oxidation substrateis typically HMF. However, it may be desirable to use a furanicoxidation substrate that is an FDCA pathway intermediate compound ormixture of FDCA pathway intermediate compounds, i.e., DFF, HMFCA, FFCA,or a mixture of any two or more thereof. This may be an attractiveoption in situations where HMF has been previously oxidized to an FDCApathway intermediate compound or mixture of intermediate compounds, andthe intermediate compound(s) is (are) available for use as a rawmaterial. When such intermediates are used as furanic oxidationsubstrates in the oxidative processes of the present disclosure, theresulting FDCA pathway product is typically FDCA, but it may also be adifferent FDCA pathway intermediate compound that is “downstream” (froman oxidation standpoint) in the FDCA pathway, of the FDCA pathwayintermediate employed as the furanic oxidation substrate.

The oxidation feedstock may contain other agents or residual componentsthat are soluble or insoluble in the oxidation feedstock. For example,the oxidation feedstock may be a crude oxidation feedstock of HMF, orother furanic oxidation substrate, and the oxidation solvent. The term“crude feedstock” refers herein to a feedstock that, in addition tocomprising the desired furanic oxidation substrate, also comprisesimpurities and/or by-products related to the production, isolation,and/or purification of the desired furanic oxidation substrate. Forexample, the oxidation feedstock, may, in addition, comprise certainbiomass-related components that originate from biomass or areby-products which are generated in the conversion of biomass to a sugar(by, for example, thermal, chemical, mechanical, and/or enzymaticdegradative means), where such sugar is subsequently converted to HMF.Thus, the oxidation feedstock may also comprise a component selectedfrom the group consisting of a polysaccharide (including, for example, acellulose (e.g., a lignocellulose, a hemicellulose, and the like),starch, and the like), an oligosaccharide (e.g., a raffinose, amaltodextrin, a cellodextrin, and the like), a monosaccharide (e.g.,glucose, fructose, galactose, mannose, xylose, rabbinose, and the like),a disaccharide (e.g., sucrose, lactose, maltose, cellobiose and thelike), furanic substrates such as furfural, oligomeric or polymerichumin by-products (humins) and residual mineral acids. Similarly, theoxidation feedstock may be a crude feedstock of HMF oxidation productscomprising HMF and/or FDCA pathway intermediate compounds.

In addition to the high yields and high selectivities observed,oxidation processes of the present disclosure produce FDCA pathwayproducts, such as, for example, FDCA at relatively high concentrationsin a resulting product solution. The high productivity levels obtainedfrom the processes described herein are believed to be due to thecombined use of the novel heterogeneous oxidation catalysts employed andthe properties of the oxidation solvent.

As used herein, the term, “oxidation solvent” refers to a solvent thatis an organic solvent or a multi-component solvent in which the furanicoxidation substrate and the desired FDCA pathway product are eachseparately soluble at a minimum level of at least 2% by weight at thetemperature at which the contacting (oxidation) step is conducted.Typically, the oxidation solvent is one in which the FDCA pathwayproduct has a solubility of at least 3 wt %, at least 4 wt %, and moretypically, at least 5 wt %, at least 6 wt %, at least 7 wt %, at least 8wt %, at least 9 wt %, at least 10 wt %, at least 11 wt %, at least 12wt %, at least 13 wt %, at least 14 wt %, or at least 15 wt %, asmeasured at the temperature at which the contacting step is carried out.In some embodiments, the FDCA pathway product has a solubility thatranges from between 2-4 wt %, 3-5 wt %, 4-6 wt %, 5-7 wt %, 6-8 wt %,7-9 wt %, 8-10 wt %, 9-11 wt %, 10-12 wt %, 11-13 wt %, 12-14 wt %, or13-15% or is within a range defined by any of two of the aforementionedweight percentages. The solubility of the FDCA pathway product in acandidate organic solvent or candidate multi-component solvent can bereadily determined using known methods, as well as the method describedin Example 1.

Without wishing to be bound by theory, the oxidation solvents employedin the present disclosure are believed to facilitate the efficientconversion of furanic oxidation substrate to FDCA pathway product(catalyzed by the high performing catalysts of the present disclosure)by, among other things, eliminating product precipitation that may leadto reactor/catalyst fouling. Moreover, the relatively highconcentrations of FDCA and FDCA intermediate compounds that may beachieved in the processes of the present disclosure results in highprocess productivity and less costly solvent removal, in contrast toprocesses that employ poor solvents such as, for example water or theacetic acid-water mixtures described in U.S. Pat. No. 7,700,788. Thus,the present disclosure provides processes that are particularlyattractive for the commercial scale production of FDCA, and relatedintermediates.

When carrying out the oxidation processes of the present disclosure, thefuranic oxidation substrate may be present in the oxidation feedstock atany concentration up to its solubility limit, in circumstances where thefeedstock is a solution. In some embodiments, the concentration offuranic oxidation substrate in the oxidation feedstock is at least 1 wt%, at least 2 wt %, at least 3 wt %, at least 4 wt %, at least 5 wt %,at least 6 wt %, at least 7 wt %, at least 8 wt %, at least 9 wt %, atleast 10 wt %, at least 11 wt %, at least 12 wt %, at least 13 wt %, atleast 14 wt %, or at least 15 wt % by weight of the oxidation feedstock.In some embodiments, the concentration of furanic oxidation substrate inthe oxidation feedstock ranges from 1-3 wt %, 2-4 wt %, 3-5 wt %, 4-6 wt%, 5-7 wt %, 6-8 wt %, 7-9 wt %, 8-10 wt %, 9-11 wt %, 10-12 wt %, 11-13wt %, 12-14 wt %, or 13-15% or is within a range defined by any of twoof the aforementioned weight percentages. Typically, the furanicoxidation substrate is present in the oxidation feedstock at aconcentration of at least 5 wt %. More typically, the furanic oxidationsubstrate is present in the oxidation feedstock at a concentration of atleast 6 wt %, or at least 7 wt %, or at least 8 wt %, or at least 9 wt%, or at least 10 wt %, or at least 11 wt %, or at least 12 wt %, or atleast 13 wt %, or at least 14 wt %, or at least 15 wt % at thetemperature at which the contacting (oxidation) step is conducted. Insome embodiments, the furanic oxidation substrate is present in theoxidation feedstock at the temperature at which the contacting(oxidation) step is conducted in a concentration that ranges frombetween 6-8 wt %, 7-9 wt %, 8-10 wt %, 9-11 wt %, 10-12 wt %, 11-13 wt%, 12-14 wt %, or 13-15% or is within a range defined by any of two ofthe aforementioned weight percentages.

Organic solvents that exhibit the requisite minimal solvatingrequirements for the furanic oxidation substrate and FDCA are suitablefor use in the practice of the present disclosure, either alone or as acomponent of a multi-component solvent. Applicants have discovered, inparticular, that the use of aprotic organic solvents, in combinationwith the catalysts and conditions described herein, appear to facilitatethe high productivities observed with respect to the processes of thepresent disclosure. Therefore, in some embodiments, the oxidationsolvent comprises an aprotic organic solvent (e.g., an ether, an ester,a ketone, and the like) either alone (i.e., as a single-componentsolvent) or as a component of a multi-component solvent. When used in amulti-component solvent, the aprotic organic solvent is typicallymiscible with the other component(s) of the multi-component solvent. Theterm “multi-component solvent” refers herein to a mixture of two, three,or more solvent species. Multi-component solvents employed in thepractice of the present disclosure may comprise two or more solventspecies selected from the group consisting of a first organic solventspecies, a second organic solvent species, and water. When themulti-component solvent comprises water and an organic solvent, theorganic solvent is a water-miscible organic solvent. Typically, thewater-miscible organic solvent is a water-miscible aprotic organicsolvent.

With respect to the processes of the present disclosure, it should benoted that candidate component solvents for the multi-component solventshould not be limited to solvents in which the furanic oxidationsubstrate and desired FDCA pathway product are highly soluble.Applicants have discovered that multi-component solvents may exhibit asynergistic solvating effect with respect to FDCA, even when FDCA ispoorly soluble in each component solvent. For example, FDCA has poorsolubility in water. Applicants have discovered that, even when pairedwith a water-miscible organic solvent having poor FDCA-solvatingcapabilities, the combination of water and the water-miscible organicsolvent exhibits enhanced FDCA-solvating capability.

Illustrative multi-component solvents that exhibit this effect includethose that comprise water and a water-miscible aprotic organic solvent.Exemplary water-miscible aprotic solvents suitable for use in thepractice of the present disclosure include tetrahydrofuran, a glyme,dioxane, a dioxolane, dimethylformamide, dimethylsulfoxide, sulfolane,acetone, N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”),gamma-valerolactone, and the like. Preferably, the water-miscibleaprotic organic solvent is an ether, such as, for example, a glyme,dioxane (1,4-dioxane), a dioxolane (e.g., 1,3-dioxolane),tetrahydrofuran, and the like. Glymes that are suitable for use in thepractice of the present disclosure include, for example, monoglyme(1,2-dimethoxyethane, “DME”), ethyl glyme, diglyme (diethylene glycoldimethyl ether), ethyl diglyme, triglyme, butyl diglyme, tetraglyme, apolyglyme, a highly ethoxylated diether of a high molecular weightalcohol (“higlyme”), and the like. Often, the oxidation solvent is amulti-component solvent comprising water and a water-miscible aproticorganic solvent that is glyme, diglyme, or dioxane.

In some embodiments, the multi-component solvent comprises water anddioxane. In some embodiments, the multi-component solvent compriseswater and DME. In some embodiments, the multi-component solventcomprises water and diglyme. In some embodiments, the multi-componentsolvent comprises water and triglyme. In some embodiments, themulti-component solvent comprises water and tetraglyme. In someembodiments, the multi-component solvent comprises water and higlyme. Insome embodiments, the multi-component solvent comprises water and NMP.In some embodiments, the multi-component solvent comprises water andMEK. In some embodiments, the multi-component solvent comprises waterand gamma-valerolactone.

Example 1 describes a solubility study that examined the solubility ofFDCA in: (1) diglyme only; (2) dioxane only; (3) water only; (4) amulti-component solvent made up of 4:1 (v/v) dioxane:H₂O; and (5) amulti-component solvent made up of 1:1 (v/v) glyme:H₂O. The results aredepicted in a plot of FDCA solubility as a function of temperature inFIG. 3. Although FDCA exhibits relatively low solubilities in water(less than 2% by weight at temperatures in the range of from 22° C. to140° C.), dioxane (less than 2% by weight at temperatures in the rangeof from 22° C. to 100° C.), and diglyme (less than 2% by weight attemperatures in the range of from 22° C. to 100° C.), it surprisinglyexhibits high solubilities in multi-component solvents of, for example,4:1 dioxane:H₂O (v:v) (from 4% by weight to 11% by weight attemperatures in the range of from 22° C. to 140° C.) and 1:1diglyme:water (v:v) (from just below 2% by weight to 9% by weight attemperatures in the range of from 22° C. to 140° C.). Thesemulti-component solvents are desirable because they facilitate theproduction of greater quantities of FDCA pathway product with relativelyless solvent (for example, as compared to water only as a solvent) thatwould typically need to be removed during product recovery operations.

Organic solvents and additional multi-component solvents suitable foruse as an oxidation solvent in the practice of the present disclosurecan be readily identified using the assay method described in Example 1.

In some embodiments, the composition of the oxidation solvent may takeinto consideration the requirements of further downstream processes(e.g., to facilitate product recovery, purification, and the like), orupstream processes (e.g., the conversion of a sugar to the furanicoxidation substrate). For example, in certain embodiments it may bedesirable to employ an oxidation solvent that is a multi-componentsolvent comprising a light solvent and a heavy solvent. The term “lightsolvent” refers to a solvent having a boiling point at a certainpressure that occurs at a temperature that is less than the boilingpoint (temperature) of the heavy solvent at the same pressure.Conversely, the term “heavy solvent” refers to a solvent having aboiling point at a certain pressure that occurs at a temperature that ishigher than the boiling point (temperature) of the light solvent at thesame pressure. When the multi-component solvent comprises water and awater-miscible organic solvent, the water-miscible organic solvent maybe a light water-miscible organic solvent (i.e., a water-miscibleorganic solvent having a boiling point that occurs at a temperature lessthan the boiling point of water) or it may be a heavy water-miscibleorganic solvent (i.e., a water-miscible organic solvent having a boilingpoint that occurs at a temperature higher than the boiling point ofwater). Typically, the light and heavy water-miscible organic solventare a light and heavy aprotic organic solvent, respectively. Exemplarylight water-miscible (and aprotic) organic solvents employed with waterin a multi-component solvent include, for example, glyme, a dioxolane(e.g., 1,3-dioxolane), and tetrahydrofuran, and the like. Exemplaryheavy water-miscible (and aprotic) organic solvents employed with waterin a multi-component solvent include, for example, dioxane, ethyl glyme,diglyme (diethylene glycol dimethyl ether), ethyl diglyme, triglyme,butyl diglyme, tetraglyme, a polyglyme, and the like. In someembodiments (e.g., continuous reactor systems), all or a portion of theoxidation solvent or component thereof may be removed from theproduction solution (e.g., via distillation) and recycled to thereaction mixture. It such embodiments, it may be desirable to employ amulti-component solvent having a composition that corresponds to anazeotrope or which is capable of forming an azeotrope (i.e., an“azeotropic composition”) at a temperature employed during the oxidationstep (i.e., contacting step), or at a temperature employed during aprocess that is upstream or downstream of the oxidation step. Use ofsuch multi-component solvents having an azeotropic composition mayfacilitate the recycling of the oxidation solvent (as part of theazeotropic composition) to the oxidation step, or to processes thatoccur upstream and/or downstream of the oxidation step.

In some embodiments, the water-miscible organic solvent species is atleast 5 volume % (vol %), at least 10 vol %, at least 15 vol %, at least20 vol %, at least 25 vol %, at least 30 vol %, at least 35 vol %, atleast 40 vol %, at least 45 vol %, at least 50 vol %, at least 55 vol %,at least 60 vol %, at least 65 vol %, at least 70 vol %, at least 75 vol%, at least 80 vol %, at least 85 vol %, at least 90 vol %, or at least95 vol % of the multi-component solvent; and correspondingly, water istypically less than 95 vol %, less than 90 vol %, less than 85 vol %,less than 80 vol %, less than 75 vol %, less than 70 vol %, less than 65vol %, less than 60 vol %, less than 55 vol %, less than 50 vol %, lessthan 45 vol %, less than 40 vol %, less than 35 vol %, less than 30 vol%, less than 25 vol %, less than 20 vol %, less than 15 vol %, less than10 vol %, or less than 5 vol %, respectively, of the multi-componentsystem.

In some embodiments, the multi-component solvent comprises water in arange from or any number in between 1-5 wt % and a water-miscibleorganic solvent in a range from or any number in between 99-95 wt %. Insome embodiments, the multi-component solvent comprises water in a rangefrom or any number in between 5-10 wt % and a water-miscible organicsolvent in a range from or any number in between 95-90 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 10-15 wt % and a water-miscible organic solventin a range from or any number in between 90-85 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 15-20 wt % and a water-miscible organic solventin a range from or any number in between 85-80 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 20-25 wt % and a water-miscible organic solventin a range from or any number in between 80-75 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 25-30 wt % and a water-miscible organic solventin a range from or any number in between 75-70 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 30-35 wt % and a water-miscible organic solventin a range from or any number in between 70-65 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 35-40 wt % and a water-miscible organic solventin a range from or any number in between 65-60 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 40-45 wt % and a water-miscible organic solventin a range from or any number in between 60-55 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 45-50 wt % and a water-miscible organic solventin a range from or any number in between 65-50 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 50-55 wt % and a water-miscible organic solventin a range from or any number in between 50-45 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 55-60 wt % and a water-miscible organic solventin a range from or any number in between 45-40 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 60-65 wt % and a water-miscible organic solventin a range from or any number in between 40-35 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 65-70 wt % and a water-miscible organic solventin a range from or any number in between 35-30 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 70-75 wt % and a water-miscible organic solventin a range from or any number in between 30-25 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 75-80 wt % and a water-miscible organic solventin a range from or any number in between 25-20 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 80-85 wt % and a water-miscible organic solventin a range from or any number in between 20-15 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 85-90 wt % and a water-miscible organic solventin a range from or any number in between 15-10 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 90-95 wt % and a water-miscible organic solventin a range from or any number in between 10-5 wt %. In some embodiments,the multi-component solvent comprises water in a range from or anynumber in between 95-99 wt % and a water-miscible organic solvent in arange from or any number in between 5-1 wt %.

In some embodiments, the volume ratio of water to water-miscible organicsolvent is in the range from or any number in between 1:6 to 6:1. Incertain embodiments, the volume ratio is from or any number in between1:4 to 4:1 water:water-miscible organic solvent. In other embodiments,the volume ratio is from or any number in between 1:4 to 3:1 water:watermiscible organic solvent. In other embodiments, the volume ratio is fromor any number in between 1:3 to 3:1 water:water miscible organicsolvent. In certain embodiments, the volume ratio is 1:1water:water-miscible organic solvent.

In some embodiments, the multi-component solvent comprises water and twodifferent water-miscible organic solvents. Typically both of thewater-miscible organic solvents are water-miscible aprotic organicsolvents. Each of the two water-miscible aprotic solvents can beindependently selected from the group of tetrahydrofuran, a glyme, adioxane, a dioxolane, dimethylformamide, dimethylsulfoxide, sulfolane,acetone, N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”),and gamma-valerolactone. One or both of the water-miscible aproticorganic solvent can be an ether, such as, for example, a glyme, dioxane(for example 1,4-dioxane), dioxolane (e.g., 1,3-dioxolane),tetrahydrofuran, and the like. Glymes include, for example, monoglyme(1,2-dimethoxyethane, “DME”), ethyl glyme, diglyme (diethylene glycoldimethyl ether), ethyl diglyme, triglyme, butyl diglyme, tetraglyme, apolyglyme, a highly ethoxylated diether of a high molecular weightalcohol (“higlyme”), and the like.

In some embodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 1:1:1 (v:v:v). In someembodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 1:2:1 (v:v:v). In someembodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 1:2:2 (v:v:v). In someembodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 2:1:1 (v:v:v).

In some embodiments, the multi-component solvent comprises water and twodifferent water-miscible organic solvents with the relative amounts ofwater to the first and second water-miscible organic solvents as shownin Table A.

TABLE A Weight percent Weight percent Weight percent of first water- ofsecond water- of water miscible organic miscible organic in multi-solvent in solvent in multi- component multi-component component solventsystem solvent system solvent system 1-5% 90-98% 1-5% 1-5% 85-94%  5-10%1-5% 80-89% 10-15% 1-5% 75-84% 15-20% 1-5% 70-79% 20-25% 1-5% 65-74%25-30% 1-5% 60-69% 30-35% 1-5% 55-64% 35-40% 1-5% 50-59% 40-45% 1-5%45-54% 45-50% 1-5% 40-49% 50-55% 1-5% 35-44% 55-60% 1-5% 30-39% 60-65%1-5% 25-34% 65-70% 1-5% 20-29% 70-75% 1-5% 15-24% 75-80% 1-5% 10-19%80-85% 1-5%  5-14% 85-90% 1-5% 1-9% 90-94%  5-10% 85-94% 1-5%  5-10%80-90%  5-10%  5-10% 75-85% 10-15%  5-10% 70-80% 15-20%  5-10% 65-75%20-25%  5-10% 60-70% 25-30%  5-10% 55-65% 30-35%  5-10% 50-60% 35-40% 5-10% 45-55% 40-45%  5-10% 40-50% 45-50%  5-10% 35-45% 50-55%  5-10%30-40% 55-60%  5-10% 25-35% 60-65%  5-10% 20-30% 65-70%  5-10% 15-25%70-75%  5-10% 10-20% 75-80%  5-10%  5-15% 80-85%  5-10%  1-10% 85-89%10-15% 80-89% 1-5% 10-15% 75-85%  5-10% 10-15% 70-80% 10-15% 10-15%65-75% 15-20% 10-15% 60-70% 20-25% 10-15% 55-65% 25-30% 10-15% 50-60%30-35% 10-15% 45-55% 35-40% 10-15% 40-50% 40-45% 10-15% 35-45% 45-50%10-15% 30-40% 50-55% 10-15% 25-35% 55-60% 10-15% 20-30% 60-65% 10-15%15-25% 65-70% 10-15% 10-20% 70-75% 10-15%  5-15% 75-80% 10-15%  1-10%80-84% 15-20% 75-84% 1-5% 15-20% 70-80%  5-10% 15-20% 65-75% 10-15%15-20% 60-70% 15-20% 15-20% 55-65% 20-25% 15-20% 50-60% 25-30% 15-20%45-55% 30-35% 15-20% 40-50% 35-40% 15-20% 35-45% 40-45% 15-20% 30-40%45-50% 15-20% 25-35% 50-55% 15-20% 20-30% 55-60% 15-20% 15-25% 60-65%15-20% 10-20% 65-70% 15-20%  5-15% 70-75% 15-20%  1-10% 75-79% 20-25%70-79% 1-5% 20-25% 65-75%  5-10% 20-25% 60-70% 10-15% 20-25% 55-65%15-20% 20-25% 50-60% 20-25% 20-25% 45-55% 25-30% 20-25% 40-50% 30-35%20-25% 35-45% 35-40% 20-25% 30-40% 40-45% 20-25% 25-35% 45-50% 20-25%20-30% 50-55% 20-25% 15-25% 55-60% 20-25% 10-20% 60-65% 20-25%  5-15%65-70% 20-25%  1-10% 70-74% 25-30% 65-74% 1-5% 25-30% 60-70%  5-10%25-30% 55-65% 10-15% 25-30% 50-60% 15-20% 25-30% 45-55% 20-25% 25-30%40-50% 25-30% 25-30% 35-45% 30-35% 25-30% 30-40% 35-40% 25-30% 25-35%40-45% 25-30% 20-30% 45-50% 25-30% 15-25% 50-55% 25-30% 10-20% 55-60%25-30%  5-15% 60-65% 25-30%  1-10% 65-69% 30-35% 60-69% 1-5% 30-35%55-65%  5-10% 30-35% 50-60% 10-15% 30-35% 45-55% 15-20% 30-35% 40-50%20-25% 30-35% 35-45% 25-30% 30-35% 30-40% 30-35% 30-35% 25-35% 35-40%30-35% 20-30% 40-45% 30-35% 15-25% 45-50% 30-35% 10-20% 50-55% 30-35% 5-15% 55-60% 30-35%  1-10% 60-64% 35-40% 55-64% 1-5% 35-40% 50-60% 5-10% 35-40% 45-55% 10-15% 35-40% 40-50% 15-20% 35-40% 35-45% 20-25%35-40% 30-40% 25-30% 35-40% 25-35% 30-35% 35-40% 20-30% 35-40% 35-40%15-25% 40-45% 35-40% 10-20% 45-50% 35-40%  5-15% 50-55% 35-40%  1-10%55-59% 40-45% 50-59% 1-5% 40-45% 45-55%  5-10% 40-45% 40-50% 10-15%40-45% 35-45% 15-20% 40-45% 30-40% 20-25% 40-45% 25-35% 25-30% 40-45%20-30% 30-35% 40-45% 15-25% 35-40% 40-45% 10-20% 40-45% 40-45%  5-15%45-50% 40-45%  1-10% 50-54% 45-50% 45-54% 1-5% 45-50% 40-50%  5-10%45-50% 35-45% 10-15% 45-50% 30-40% 15-20% 45-50% 25-35% 20-25% 45-50%20-30% 25-30% 45-50% 15-25% 30-35% 45-50% 10-20% 35-40% 45-50%  5-15%40-45% 45-50%  1-10% 45-49% 50-55% 40-49% 1-5% 50-55% 35-45%  5-10%50-55% 30-40% 10-15% 50-55% 25-35% 15-20% 50-55% 20-30% 20-25% 50-55%15-25% 25-30% 50-55% 10-20% 30-35% 50-55%  5-15% 35-40% 50-55%  1-10%40-44% 55-60% 35-44% 1-5% 55-60% 30-40%  5-10% 55-60% 25-35% 10-15%55-60% 20-30% 15-20% 55-60% 15-25% 20-25% 55-60% 10-20% 25-30% 55-60% 5-15% 30-35% 55-60%  1-10% 35-39% 60-65% 30-39% 1-5% 60-65% 25-35% 5-10% 60-65% 20-30% 10-15% 60-65% 15-25% 15-20% 60-65% 10-20% 20-25%60-65%  5-15% 25-30% 60-65%  1-10% 30-34% 65-70% 25-34% 1-5% 65-70%20-30%  5-10% 65-70% 15-25% 10-15% 65-70% 10-20% 15-20% 65-70%  5-15%20-25% 70-75% 20-29% 1-5% 70-75% 15-25%  5-10% 70-75% 10-20% 10-15%70-75%  5-15% 15-20% 75-80% 15-24% 1-5% 75-80% 10-20%  5-10% 75-80% 5-15% 10-15%

The contacting step is often carried out for a time sufficient toproduce a product solution comprising (soluble) FDCA pathway product ata concentration of at least 2 wt %, at least 3 wt %, at least 4 wt %, atleast 5 wt %, at least 6 wt %, at least 7 wt %, at least 8 wt %, atleast 9 wt %, at least 10 wt %, at least 11 wt %, at least 12 wt %, atleast 13 wt %, at least 14 wt %, or at least 15 wt % or at aconcentration that is within a range defined by any two of theaforementioned values. Correspondingly, when a product solution isproduced that comprises the (soluble) FDCA pathway product it isproduced at a concentration of at least 2 wt %, at least 3 wt %, atleast 4 wt %, at least 5 wt %, at least 6 wt %, at least 7 wt %, atleast 8 wt %, at least 9 wt %, at least 10 wt %, at least 11 wt %, atleast 12 wt %, at least 13 wt %, at least 14 wt %, or at least 15 wt %)or a at concentration that is within a range defined by any two of theaforementioned values. The term “product solution” refers herein to asolution of soluble FDCA pathway product and other soluble components ofthe reaction mixture in the oxidation solvent. The phrase “a timesufficient to produce a product solution comprising the FDCA pathwayproduct at a concentration of” is used herein to refer to a minimumamount of time required to produce the specified concentration of theFDCA pathway product in the product solution.

More typically, the contacting step is carried out for a time sufficientto produce a product solution comprising the FDCA pathway product at aconcentration of at least 6 wt %, at least 7 wt %, at least 8 wt %, atleast 9 wt %, at least 10 wt %, at least 11 wt %, at least 12 wt %, atleast 13 wt %, at least 14 wt %, or at least 15 wt % or at aconcentration that is within a range defined by any two of theaforementioned values. Correspondingly, when a product solution isproduced that comprises the FDCA pathway product it is produced at aconcentration of at least 6 wt %, at least 7 wt %, at least 8 wt %, atleast 9 wt %, at least 10 wt %, at least 11 wt %, at least 12 wt %, atleast 13 wt %, at least 14 wt %, or at least 15 wt %, respectively or aconcentration that is within a range defined by any two of theaforementioned values.

Heterogeneous oxidation catalysts employed in the practice of thepresent disclosure typically have the noble metal dispersed on theinternal and external surfaces of the support. The term “noble metal”refers herein to ruthenium, rhodium, palladium, silver, osmium, iridium,platinum or gold. In certain preferred embodiments, the metal isselected from the group consisting of platinum, gold, and a combinationthereof. Typically, the metal is platinum. In some embodiments, themetal is gold. The heterogeneous oxidation catalyst may further includea promoter to enhance the performance of the heterogeneous oxidationcatalyst. When the metal is platinum, gold, or combination thereof,suitable promoters include, for example, Pd, Ir, Mo, or W, and the like.

The heterogeneous oxidation catalyst typically comprises the noble metalat a total metal loading in the range of from or any number in between0.3% to 5% by weight. In some embodiments, the metal loading is in therange of from or any number in between 0.5% to 4% by weight. In someembodiments, the metal loading ranges from or any number in between 2-4wt %. In some embodiments, the metal loading is 2 wt %. In someembodiments, the metal loading is 3 wt %. In some embodiments, the metalloading is 4 wt %. When two or more metals are employed, theheterogeneous oxidation catalyst may comprise a plurality ofheterogeneous oxidation catalyst particles, each comprising the two ormore metals, or the heterogeneous oxidation catalyst may comprise amixture of heterogeneous oxidation catalyst metal-particle species,e.g., a first plurality of heterogeneous oxidation catalyst particlescomprising a first metal species and a second plurality of heterogeneousoxidation catalyst particles comprising a second metal species. Methodsfor preparing the heterogeneous oxidation catalysts employed in thepractice of the present disclosure are described in detail in sectionII, herein below, as well as in the Examples.

The solid support component of the heterogeneous oxidation catalyst maycomprise any type of material known by those having ordinary skill inthe art as being suitable for use as a catalytic support that also hasthe specific surface area requirement described herein. Suitablematerials include, for example, a metal oxide, a carbonaceous material,a polymer, a metal silicate, a metal carbide, or any composite materialprepared therefrom. Exemplary metal oxides include silicon oxide(silica), zirconium oxide (zirconia), titanium oxide (titania), oraluminum oxide (alumina), and the like. As used herein, the term“carbonaceous” refers to graphite and carbon black. Exemplary metalsilicates include, for example, an orthosilicate, a borosilicate, or analuminosilicate (e.g., a zeolite), and the like. Exemplary metalcarbides include, for example, silicon carbide, and the like. Suitablepolymeric solid support materials include polystyrene,polystyrene-co-divinyl benzene, polyamides, or polyacrylamides, and thelike.

Suitable solid support materials also include a composite materialprepared from, or comprising a binder and a material selected from thegroup consisting of a metal oxide, a carbonaceous material, a polymer, ametal silicate, and a metal carbide. In some embodiments, the binder isa resin. In other embodiments, the composite material comprises acarbonized binder and a material selected from the group consisting of ametal oxide, a carbonaceous material, a metal silicate, and a metalcarbide. In one embodiment, the composite material comprises acarbonized binder and carbon black. Methods for making such carbon-basedcomposite materials is described in PCT Application No. PCT/US15/28358,which is expressly incorporated herein by reference in its entirety.Illustrative support materials are described in the Examples herein.

In some embodiments, the solid support comprises a carbon black materialselected from the group consisting of Aditya Birla CDX-KU, Aditya BirlaCSCUB, Aditya Birla R2000B, Aditya Birla R2500UB, Aditya Birla R3500B,Aditya Birla R5000U2, Arosperse 5-183A, Asbury 5302, Asbury 5303, Asbury5345, Asbury 5348R, Asbury 5358R, Asbury 5365R, Asbury 5368, Asbury5375R, Asbury 5379, Asbury A99, Cabot Monarch 120, Cabot Monarch 280,Cabot Monarch 570, Cabot Monarch 700, Cabot Norit Darco 12x20L1, CabotVulcan XC72, Continental N120, Continental N234, Continental N330,Continental N330-C, Continental N550, Norit ROX 0.8, Orion Arosperse138, Orion Arosperse 15, Orion Color Black FW 2, Orion Color Black FW255, Orion HiBlack 40B2, Orion Hi-Black 50 L, Orion Hi-Black 50 LB,Orion Hi-Black 600 L, Orion HP-160, Orion Lamp Black 101, Orion N330,Orion Printex L6, Sid Richardson Ground N115, Sid Richardson GroundSR155, Sid Richardson SC159, Sid Richardson SC419, Timcal Ensaco 150G,Timcal Ensaco 250G, Timcal Ensaco 260G, and Timcal Ensaco 350G.

Metal impregnation of the solid support typically results in anegligible change in the specific surface, pore diameters, and specificvolume of the solid support. Heterogeneous oxidation catalysts that aresuitable for use in the present disclosure are typically prepared usinga solid support that comprises a plurality of pores and a specificsurface area in the range of from 20 m²/g to 500 m²/g, such as e.g., 20,30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 225, 250, 275,300, 325, 350, 375, 400, 425, 450, 475, or 500 m²/g or is within a rangedefined by any two of the aforementioned surface areas. Specific surfacearea can be determined using known methods, such as, for example, themethod of Bruanauer, Emmett and Teller (J. Am. Chem. Soc. 1938,60:309-311) and/or mercury porosimetry. See e.g., ASTM Test MethodsD3663, D6556, and D4567, each of which is incorporated by reference inits entirety. Typically, heterogeneous oxidation catalysts (and solidsupports) employed in the practice of the present disclosure have aspecific surface area in the range of from or any number in between 25m²/g to 250 m²/g, and sometimes in the range of from or any number inbetween 25 m²/g to 225 m²/g, or from or any number in between 25 m²/g to200 m²/g, or from or any number in between 25 m²/g to 175 m²/g, or fromor any number in between 25 m²/g to 150 m²/g, or from or any number inbetween 25 m²/g to 125 m²/g, or from or any number in between 25 m²/g to100 m²/g. These specific surface areas are relatively low when comparedto highly porous catalytic support materials that are more typicallyused in the art, such as, for example, activated carbon. The relativelylow surface area of the heterogeneous oxidation catalysts employed inthe oxidative processes of the present disclosure is believed tofavorably contribute to the high selectivity and yields observed withrespect to the conversion of the furanic oxidation substrates to FDCAand FDCA pathway intermediate compounds under substantially base-freeconditions.

Commensurate with the relatively low specific surface areas, theheterogeneous oxidation catalysts (and solid support components thereof)employed in the practice of the present disclosure also typically haverelatively moderate to low specific pore volumes when compared to otheroxidation catalysts. Heterogeneous oxidation catalysts (and solidsupport components thereof) employed in the practice of the presentdisclosure typically have a specific pore volume (determined on thebasis of pores having a diameter of 1.7 nm to 100 nm) that is, from orany number in between 0.1 cm³/g to 1.5 cm³/g, from or any number inbetween 0.1 cm³/g to 0.8 cm³/g, from or any number in between 0.1 cm³/gto 0.7 cm³/g, from or any number in between 0.1 cm³/g to 0.6 cm³/g, fromor any number in between 0.1 cm³/g to 0.5 cm³/g, from or any number inbetween 0.2 cm³/g to 0.8 cm³/g, from or any number in between 0.2 cm³/gto 0.7 cm³/g, from or any number in between 0.2 cm³/g to 0.6 cm³/g, fromor any number in between 0.2 cm³/g to 0.5 cm³/g, from or any number inbetween 0.3 cm³/g to 1 cm³/g, from or any number in between 0.3 cm³/g to0.9 cm³/g, from or any number in between 0.3 cm³/g to 0.8 cm³/g, from orany number in between 0.3 cm³/g to 0.7 cm³/g, from or any number inbetween 0.3 cm³/g to 0.6 cm³/g, or from or any number in between 0.3cm³/g to 0.5 cm³/g or within a range defined by any two of theaforementioned values, as measured by a method for determining porediameters and specific pore volumes, such as that described in E. P.Barrett, L. G. Joyner, P. P. Halenda, J. Am. Chem. Soc. (1951)73:373-380 and ASTM D4222-03 (2008) (the method referred to herein asthe “BJH method”), both of which are expressly incorporated herein byreference in their entireties, and by the method of mercury porosimetry(e.g., using a mercury porosimeter, such as, for example, theMicromeritics Autopore V 9605 Mercury Porosimeter (MicromeriticsInstrument Corp., Norcross, Ga.) in accordance with the manufacturer'sinstructions). See e.g., ASTM 3663, ASTM D-4284-12 and D6761-07 (2012),all of which are incorporated herein by reference.

Typically, the heterogeneous oxidation catalyst has a mean pore diameterin the range of from or any number in between 10 nm to 100 nm, asmeasured by the BJH method and/or mercury porosimetry. More typically,the heterogeneous oxidation catalyst has a mean pore diameter in therange of from or any number in between 10 nm to 90 nm, as measured bythe BJH method and/or mercury porosimetry. In some embodiments, the meanpore diameter is in the range of from or any number in between 10 nm to80 nm, or from or any number in between 10 nm to 70 nm, or from or anynumber in between 10 nm to 60 nm, and often from or any number inbetween 10 nm to 50 nm, as determined by the BJH method and/or mercuryporosimetry. In some embodiments, the mean pore diameter is in the rangeof from or any number in between 20 nm to 100 nm, as measured by the BJHmethod and/or mercury porosimetry. In certain of these embodiments, themean pore diameter is in the range from or any number in between 20 nmto 90 nm, or from or any number in between 20 nm to 80 nm, or from orany number in between 20 nm to 70 nm, or from or any number in between20 nm to 60 nm, or from or any number in between 10 nm to 50 nm, asdetermined by the BJH method and/or mercury porosimetry. The catalystsemployed in the practice of the present disclosure typically have arelatively high concentration of pores in the size ranges describedabove.

In some embodiments, the heterogeneous oxidation catalyst comprises asecond plurality of pores. In this embodiment, the pore sizedistribution of the heterogeneous oxidation catalyst and underlyingsolid support is bimodal, having a first distribution made up of a firstplurality of pore diameters and a second distribution made up of asecond plurality of pore diameters, with each plurality having a meanpore diameter associated with it. The second plurality of pores has amean pore diameter that is different from the mean pore diameter of thesecond plurality, yet is typically still in the range of from or anynumber in between 10 nm to 100 nm, as determined by the BJH methodand/or mercury porosimetry.

Typically, the heterogeneous oxidation catalysts comprise a pore volume,wherein at least 50% of the pore volume is attributable to pores havinga pore diameter in the range of from or any number in between 5 nm to100 nm (as determined by the BJH method and/or mercury porosimetry onthe basis of pores having a diameter of from 1.7 nm to 100 nm).Typically, the heterogeneous oxidation catalyst has a pore volume,wherein at least 60%, and in some embodiments, at least 70%, or at least80%, or at least 90% of the pore volume is attributable to pores havingpore diameter of from or any number in between 10 nm to 100 nm (asdetermined by the BJH method and/or mercury porosimetry on the basis ofpores having a diameter of from 1.7 nm to 100 nm).

In some embodiments, at least 35%, at least 40%, at least 45%, or atleast 50% of the pore volume of the heterogeneous oxidation catalystsemployed in the practice of the present disclosure (as measured by theBJH method and/or mercury porosimetry on the basis of pores having adiameter from 1.7 nm to 100 nm) is attributable to pores having a porediameter of from or any number in between 10 nm to 50 nm. For example,from or any number in between 35% to 80%, from or any number in between35% to 75%, from or any number in between 35% to 65%, from or any numberin between 40% to 80%, from or any number in between 40% to 75%, or fromor any number in between 40% to 70% of the pore volume of theheterogeneous oxidation catalyst is attributable to pores having a meanpore diameter in the range from or any number in between 10 nm to 50 nm(as measured by the BJH method and/or mercury porosimetry on the basisof pores having a diameter from 1.7 nm to 100 nm).

Typically, no more than 2.5% of the pore volume of the heterogeneousoxidation catalyst is attributable to pores having a pore diameter ofless than 10 or 5 nm. More typically, no more than 3%, or no more than4%, or no more than 5%, or no more than 10% or no more than a value thatis within a range defined by any two of the aforementioned percentagesof the pore volume of the heterogeneous oxidation catalyst isattributable to pores having a pore diameter of less than 10 or 5 nm, asdetermined by the BJH method and/or mercury porosimetry. To prepareheterogeneous oxidation catalysts that are suitable for use in thepractice of the present disclosure, solid supports are selected whichpossess the foregoing physical properties. The pore structure of thesupport material is typically retained in the finished heterogeneousoxidation catalyst after metal impregnation.

In certain preferred embodiments, the noble metal in the heterogeneousoxidation catalyst comprises or consists essentially of platinum, and insome embodiments consists of platinum, and in each case, wherein thesolid support is selected from the group consisting of silica and acarbonaceous material. In these preferred embodiments, the heterogeneousoxidation catalyst typically comprises a mean pore diameter in the rangeof from or any number in between 10 nm to 100 nm, and often in the rangeof from or any number in between 20 nm to 100 nm, as determined by theBJH method and/or mercury porosimetry.

In carrying out the processes of the present disclosure, oxygen may beprovided in neat form (i.e., O₂ only, with no other gases) or as acomponent of a mixture of gases (e.g., air, oxygen-enriched air, and thelike). The molar ratio of oxygen to the furanic oxidation substrateduring the contacting step is typically in the range of from 2:1 to10:1. In some embodiments, the molar ratio of oxygen to the furanicoxidation substrate is from 2:1 to 10:1, or from 3:1 to 5:1. During thecontacting step, oxygen is typically present at a partial pressure inthe range of from or any number in between 50 psig to 1000 psig. Moretypically, oxygen is present at a partial pressure in the range of fromor any number in between 50 psig to 200 psig. In some embodiments,oxygen is present at a partial pressure in the range from or any numberin between 50-200 psig, 100-300 psig, 200-400 psig, 300-500 psig,400-600 psig, 500-700 psig, 600-800 psig, 700-900 psig, or 800-1000psig, or within a range defined by any two of the aforementioned partialpressures.

The contacting (oxidation) step is typically carried out at atemperature in the range of from or any number in between 50° C. to 200°C. In some embodiments, the contacting step is carried out at atemperature in the range of from or any number in between 80° C. to 180°C., and in other embodiments, the contacting step carried out at atemperature in the range from or any number in between 90° C. to 160° C.or from or any number in between 100° C. to 160° C. In certain preferredembodiments, the contacting step is carried out at a temperature in therange of from or any number in between 90° C. to 180° C., and sometimesit is carried out at a temperature in the range of from or any number inbetween 110° C. to 160° C.

An illustrative process for carrying out the production of the desiredFDCA pathway product from a furanic oxidation substrate is depicted inFIG. 4. In this process, which utilizes a single oxidation reactionzone, an oxygen feed stream 110 comprising O₂ (in neat form or as acomponent of a mixture of gases) and a furanic oxidation substratefeedstock stream 100 are passed into an oxidation zone 10 to produce anFDCA pathway product stream 127 and an optional recycle stream 115,which comprises unreacted furanic oxidation substrate.

In some embodiments, it may be desirable to carry out the oxidation ofthe furanic oxidation substrate to the desired FDCA pathway product in aseries of two or more oxidation steps, where the first oxidation step isas described above, and where the second oxidation step comprises:

(b) contacting a second oxidation feedstock comprising a second furanicoxidation substrate and a second oxidation solvent with oxygen in thepresence of a second heterogeneous oxidation catalyst under conditionssufficient to form a second reaction mixture for oxidizing the secondfuranic oxidation substrate to produce a second FDCA pathway product,

wherein (the first) contacting step (a) produces a first FDCA pathwayproduct that is an FDCA pathway intermediate compound, either alone ortogether with FDCA,

wherein the second furanic oxidation substrate is the first FDCA pathwayproduct,

wherein the second reaction mixture is substantially free of added base,and

-   -   wherein the second heterogeneous oxidation catalyst comprises a        second solid support and a noble metal that may be the same or        different from the (first) noble metal in step (a), and

wherein the second heterogeneous oxidation catalyst comprises aplurality of pores and a specific surface area in the range of from orany number in between 20 m²/g to 500 m²/g, such as e.g., 20, 30, 40, 50,60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 225, 250, 275, 300, 325,350, 375, 400, 425, 450, 475, or 500 m²/g or is within a range definedby any two of the aforementioned surface areas.

The second FDCA pathway product is a downstream oxidation product of thefirst FDCA pathway product, and is typically FFCA, or FDCA. Typically,the second FDCA pathway product is FDCA. Usually, the second oxidationstep is free of added base.

Noble metals, catalyst metal loadings, solid support materials, andreaction conditions (e.g., reaction temperatures, oxygen (partial)pressure, molar ratio of oxygen to furanic oxidation substrate, and thelike) that are suitable for using in the first oxidation process arealso suitable for using in the second oxidation process. The secondheterogeneous oxidation catalyst may be the same or different than thatused in the first oxidation process (i.e., the “first” heterogeneousoxidation catalyst”). Oxidation solvents that are suitable for use inthe second oxidation feedstock are the same as those that are suitablefor use in the first oxidation process (i.e., the “first oxidationsolvent”). The multi-stage oxidation process format may be desirable ifoptimal production of the desired FDCA pathway product requires a changein reaction conditions during the course of conversion from the furanicoxidation substrate to the desired FDCA pathway product. For example, itmay be desirable to carry out the second oxidation reaction at a higheror lower temperature than the first oxidation reaction, or maintain themolar ratio of oxygen to feedstock component in the second oxidationreaction at a higher or lower ratio than in the first oxidationreaction, or maintain the partial pressure of oxygen in the secondoxidation reaction at a higher or lower partial pressure than in thefirst oxidation reaction. The composition of the second oxidationsolvent may be the same as the composition of the first oxidationsolvent or it may be different. If it is different, it may still have incommon one or more of the same solvent species component. The noblemetal in the second heterogeneous oxidation catalyst is typicallyplatinum, gold, or a combination thereof. Usually, the noble metal usedin the second heterogeneous oxidation catalyst is platinum.

In certain preferred embodiments, the noble metal in the secondheterogeneous oxidation catalyst comprises or consists essentially ofplatinum, and in some embodiments consists of platinum, and in eachcase, wherein the second solid support is selected from the groupconsisting of silica and a carbonaceous material. In these preferredembodiments, the second heterogeneous oxidation catalyst typicallycomprises a mean pore diameter in the range of from or any number inbetween 10 nm to 100 nm, and often in the range of from or any number inbetween 20 nm to 100 nm, such as e.g., 10, 20, 30, 40, 50, 60, 70, 80,90, or 100 nm or within a range defined by any two of the aforementionedmean pore diameters.

FIG. 5 provides an illustrative integrated process for carrying out theproduction of the desired FDCA pathway product in two stages, using twooxidation reaction zones in series: oxidation reaction zone 1 20 andoxidation reaction zone 2 30. In this integrated process, an oxidantfeed stream 110 comprising O₂, and a furanic oxidation substratefeedstock stream 100 are passed into oxidation reaction zone 20 toproduce oxidation reaction zone 1 product stream 120. Oxidation reactionzone 1 product stream comprises an FDCA pathway intermediate compoundand the oxidation solvent. Product stream 120, and oxidant feed stream112 comprising O₂ are then passed into a oxidation reaction zone 2 30 toproduce oxidation reaction zone product stream 130 and an optionalrecycle stream 125 which comprises unreacted furanic oxidationsubstrate. Oxidation reaction zone product stream 130 comprises anoxidized product of the FDCA pathway intermediate compound fromoxidation reaction zone 30, which may be FDCA and/or an FDCA pathwayintermediate that, in either case, is an oxidation product of the FDCApathway intermediate present in oxidation reaction zone 1 product stream120.

The processes of the present disclosure may be carried out in batch,semi-batch, or continuous reactor format using reactors known in theart, such as, for example, fixed bed reactors, trickle bed reactors,slurry phase reactors, moving bed reactors, and the like. The relativelyhigh solubilities of reactants and products (particularly, the FDCApathway product) in the oxidation solvent facilitate the use of all suchreactor formats, and particularly the fixed bed reactor format.

FDCA pathway product(s) produced by the oxidation processes describedherein may be recovered from the reaction mixture by separating theheterogeneous oxidation catalyst from a product solution comprising theFDCA pathway product(s) and the oxidation solvent. The product solutionincludes the oxidation solvent and soluble components of the reactionmixture and excludes the heterogeneous oxidation catalyst. The productsolution may be further concentrated with respect to the solublecomponents by removal of a portion of the oxidation solvent. Oxidationsolvent removal may be accomplished by evaporation (e.g., by using anevaporator), distillation, and the like.

Alternatively, or further to the isolation step, the FDCA pathwayproduct may be purified. Preferably, the FDCA pathway product ispurified by crystallization. Thus, in one embodiment, the presentdisclosure provides a process for producing a crystalline FDCA pathwayproduct composition, the method comprising:

providing a crystallization solution comprising an FDCA pathway productand a crystallization solvent that is a solvent selected from the groupconsisting of an organic solvent and a multi-component solvent;initiating crystallization of the FDCA pathway product; and producing aplurality of FDCA pathway product crystals of different particle sizes.

As used herein, the term “crystallization solvent” refers to a solventfrom which the FDCA pathway product can be crystallized when conditionsare imposed that cause a reduction in solubility of the FDCA pathwayproduct in the crystallization solvent (e.g., temperature reduction(cooling) or solvent removal). The crystallization solvent may be water,an organic solvent, or a multi-component solvent comprising water and awater-miscible organic solvent or two or more organic solvent species.The crystallization process may directly follow the oxidation process(e.g., either a single stage oxidation process or multi-stage oxidationprocess), or it may follow other unit operations downstream of theoxidation process.

When crystallization follows FDCA pathway product generation, thecrystallization solution is typically a product solution comprising theFDCA pathway product and the oxidation solvent. In such embodiment,therefore, the crystallization solvent is the same as the oxidationsolvent (e.g., the first oxidation solvent (single stage oxidation) orthe second oxidation solvent (for two-stage oxidation)). Some solventsthat are suitable for use in the oxidation solvent are also suitable foruse as the crystallization solvent.

Industrial solution phase crystallizations are typically performed byintroducing a saturated (or super-saturated) solution of the productinto a crystallizer in which the solution is subjected tocrystallization conditions, and crystallization is initiated by, forexample, lowering the temperature or concentrating the solution bysolvent evaporation (i.e., solvent removal), or a combination of both.Solvent evaporation may be used to concentrate the solution to initiatecrystallization, and may also be used to adjust the solvent compositionto lower the solubility of the FDCA pathway product. As used herein, theterm “crystallization conditions” refers to an adjustment in temperatureand/or adjustment in crystallization solution concentration and/oradjustment in crystallization solution composition that causes theinitiation of crystallization of the FDCA pathway product.

In one embodiment where crystallization conditions include a temperatureadjustment, the present disclosure provides a process for producing acrystalline FDCA preparation, the method comprising:

providing a crystallization solution comprising the FDCA pathway productand a crystallization solvent at a first temperature in the range of orany number in between 50° C. to 220° C., such as e.g., 50, 60, 70, 80,90, 100, 110, 120, 130, 140, 150, 160, 180, 190, 200, 210, or 220° C. orwithin a range defined by any two of the aforementioned temperatures;and

cooling the crystallization solution to a second temperature that islower than the first temperature to form a plurality of FDCA pathwayproduct crystals of different particle sizes.

Cooling reduces the solubility of the FDCA pathway product in thecrystallization solvent, causing crystals of FDCA pathway product toform in the solution. The first temperature is typically in the range offrom or any number in between 60° C. to 180° C., such as e.g., 60, 70,80, 90, 100, 110, 120, 130, 140, 150, 160, or 180° C. or within a rangedefined by any two of the aforementioned temperatures. In someembodiments, the first temperature is in the range from or any number inbetween 70° C. to 150° C. such as e.g., 70, 80, 90, 100, 110, 120, 130,140, or 150° C. or within a range defined by any two of theaforementioned temperatures. When the crystallization solution iscooled, it is typically cooled to a temperature that is at or below 60°C., such as e.g., equal to or less than 60, 50, 40, 30, 20, 10, 5, or 0°C. or within a range defined by any two of the aforementionedtemperatures. More typically, it is cooled to a temperature at or below50° C. or at or below 40° C. such as, e.g., equal to or less than 50,40, 30, 20, 10, 5, or 0° C. or within a range defined by any two of theaforementioned temperatures.

In an embodiment where solvent removal (evaporation) is used to initiatecrystallization, the present disclosure provides a method for producinga crystalline FDCA preparation, the method comprising:

(a) providing a first crystallization solution comprising FDCA and afirst crystallization solvent selected from the group consisting ofwater, an organic solvent, and combinations thereof;

(b) removing a first portion of the first crystallization solvent fromthe first crystallization solution to produce a first FDCA pathwayproduct slurry, wherein the first FDCA pathway product slurry comprisesa first plurality of FDCA pathway product crystals and a second portionof the first crystallization solvent; and

(c) separating the first plurality of FDCA pathway product crystals fromthe second portion of the first crystallization solvent.

In a further embodiment, the first plurality of FDCA pathway productcrystals are recrystallized, by conducting the following additionalsteps:

(d) dissolving the first plurality of FDCA crystals in a secondcrystallization solvent to produce a second crystallization solutioncomprising FDCA and the second crystallization solvent; and

(e) removing a first portion of the second crystallization solvent fromthe second crystallization solution to produce a second FDCA pathwayproduct slurry, wherein the second FDCA pathway product slurry comprisesa second plurality of FDCA pathway product crystals and a second portionof the second crystallization solvent; and

(f) separating the second plurality of FDCA pathway product crystalsfrom the second portion of the second crystallization solvent.

Removal of a portion of the crystallization solvent can be accomplishedusing known methods for removing solvents from a solution, such as, forexample, evaporation, or distillation, and the like. Solvent removal maybe facilitated by raising the temperature of the crystallizationsolution to effect vaporization of the crystallization solvent, orcomponent thereof, resulting in one portion of the crystallizationsolvent being in a liquid phase and another portion being in a vaporphase, which is removed. Solvent removal results in an increase inconcentration of the FDCA pathway product causing it to crystallize,thereby resulting in a slurry of FDCA pathway product crystals in acontinuous liquid phase. Often, one or both of the first and secondcrystallization solvents is/are a multi-component solvent, whereremoving a first portion of the first and/or second crystallizationsolvents may involve removing all or part of one of the components ofthe multi-component solvent, and less or none of the other components.In these embodiments, the multi-component solvent may comprise oneorganic solvent species that is a light organic solvent and a secondorganic species that is a heavy organic solvent; or alternatively, itmay comprise water and an organic solvent that is either a heavy orlight, water-miscible organic solvent.

Separation of the first plurality of FDCA pathway product crystals andthe second plurality of FDCA pathway product crystals from the secondportion of the first crystallization solvent and the second portion ofthe second crystallization solvent, respectively, can be accomplishedusing known methods for separating solids from liquids, such as, forexample, filtration, centrifugation, and the like.

The dissolving step (step (c)) is typically carried out at an elevatedtemperature to facilitate the dissolution of the first plurality of FDCApathway product crystals in the second crystallization solvent. Thetemperature will depend on the crystallization solvent employed, but canbe readily determined by raising the temperature, and optionally addingmore second crystallization solvent, until the first plurality of FDCApathway product crystals has dissolved completely. Typically, thedissolving step is carried out at a temperature in the range from or anynumber in between 50° C. to 220° C., such as e.g., 50, 60, 70, 80, 90,100, 110, 120, 130, 140, 150, 160, 180, 190, 200, 210, or 220° C. orwithin a range defined by any two of the aforementioned temperatures.Often, the dissolving step is carried out at a temperature in the rangefrom or any number in between 60° C. to 180° C., or in the range from orany number in between 70° C. to 150° C. such as e.g., 60, 70, 80, 90,100, 110, 120, 130, 140, 150, 160, 170, or 180° C. or within a rangedefined by any two of the aforementioned temperatures. In someembodiments, the dissolving step is carried out at the higher end ofthese ranges, such as, for example, in the range from or any number inbetween 100° C. to 220° C., or from or any number in between 150° C. to220° C., such as e.g., 100, 110, 120, 130, 140, 150, 160, 180, 190, 200,210, or 220° C. or within a range defined by any two of theaforementioned temperatures.

The first and second crystallization solvent may be the same ordifferent. In certain embodiments, at least one of the first and secondcrystallization solvents is a multi-component solvent that comprises acomponent solvent species common to both crystallization solvents. Insome embodiments, the first crystallization solution comprising the FDCApathway product is a product solution comprising the FDCA pathwayproduct that results from the oxidation of the furanic oxidationsubstrate as described hereinabove. In other embodiments, the firstcrystallization solvent is not the same as the oxidation solvent used inthe prior oxidation step. In these embodiments, all or a portion of theoxidation solvent may be removed prior to the crystallization step, by,for example, evaporation, and the like. The resulting solids can bedissolved in a different solvent (e.g., water or a different organicsolvent species) or different multi-component solvent (i.e., a solventthat does not have the same composition as the oxidation solvent) toprepare the first crystallization solution.

In a specific embodiment, the crystallization solvent is amulti-component solvent comprising water and a water-miscible organicsolvent. Thus, in a further embodiment, the present disclosure providesa process for producing a crystalline preparation of an FDCA pathwayproduct, the process comprising:

providing a crystallization solution comprising an FDCA pathway productand a crystallization solvent that is a multi-component solventcomprising water and a water-miscible organic solvent;

initiating crystallization of the FDCA pathway product; and

producing a plurality of FDCA pathway product crystals of differentparticle sizes.

In this embodiment, the water-miscible organic solvent is typically awater-miscible aprotic organic solvent. In an exemplary embodiment, thewater-miscible aprotic organic solvent is an ether, such as, for exampledioxane, dioxolane, diglyme, and the like. To illustrate the benefit ofsuch solvent system, FIG. 3 shows the FDCA solubility relationship inrepresentative solvent compositions of the disclosure in comparison towater, dioxane, dioxolane (e.g., 1,3-dioxolane), and diglyme. The highsolubility of FDCA in the solvent compositions of the disclosuresenables the preparation of saturated solutions of FDCA in preparationfor purification by crystallization. FIG. 3 also shows that, byadjusting the solvent composition by removing water or the organicsolvent (or an azeotropic mixture of water and the organic solvent), itis possible to produce a solvent composition that is organic solventrich (in the cases in which the chosen organic solvent is less volatilethan water), or a solvent composition that is water rich (in the casethat the chosen organic solvent is more volatile than water). FIG. 3demonstrates that FDCA is considerably less soluble in water or organicsolvents than the solvent compositions of the disclosure. The saturatedsolutions of FDCA may be subjected to crystallization conditions bylowering the temperature or by solvent evaporation to adjust the solventcomposition, or both.

Exemplary water-miscible aprotic solvents that are suitable for use inthe crystallization processes of the present disclosure includetetrahydrofuran, a glyme, a dioxane, a dioxolane, dimethylformamide,dimethylsulfoxide, sulfolane, acetone, N-methyl-2-pyrrolidone (“NMP”),methyl ethyl ketone (“MEK”), gamma-valerolactone, and the like.Preferably, the water-miscible aprotic organic solvent is an ether, suchas, for example, a glyme, dioxane (for example 1,4-dioxane), dioxolane(e.g., 1,3-dioxolane), tetrahydrofuran, and the like. Glymes that aresuitable for use in the practice of the present disclosure include, forexample, monoglyme (1,2-dimethoxyethane, “DME”), ethyl glyme, diglyme(diethylene glycol dimethyl ether), ethyl diglyme, triglyme, butyldiglyme, tetraglyme, a polyglyme, a highly ethoxylated diether of a highmolecular weight alcohol (“higlyme”), and the like. Often, thewater-miscible aprotic organic solvent is glyme, diglyme, or dioxane.

In some embodiments, the water-miscible organic solvent species is atleast 5 vol %, at least 10 vol %, at least 15 vol %, at least 20 vol %,at least 25 vol %, at least 30 vol %, at least 35 vol %, at least 40 vol%, at least 45 vol %, at least 50 vol %, at least 55 vol %, at least 60vol %, at least 65 vol %, at least 70 vol %, at least 75 vol %, at least80 vol %, at least 85 vol %, at least 90 vol %, or at least 95 vol % ofthe multi-component solvent or within a range defined by any two of theaforementioned values; and correspondingly, water is typically less than95 vol %, less than 90 vol %, less than 85 vol %, less than 80 vol %,less than 75 vol %, less than 70 vol %, less than 65 vol %, less than 60vol %, less than 55 vol %, less than 50 vol %, less than 45 vol %, lessthan 40 vol %, less than 35 vol %, less than 30 vol %, less than 25 vol%, less than 20 vol %, less than 15 vol %, less than 10 vol %, or lessthan 5 vol %, respectively, of the multi-component system or within arange defined by any two of the aforementioned values.

In some embodiments, the multi-component solvent comprises water in arange from or any number in between 1-5 wt % and a water-miscibleorganic solvent in a range from or any number in between 99-95 wt %. Insome embodiments, the multi-component solvent comprises water in a rangefrom or any number in between 5-10 wt % and a water-miscible organicsolvent in a range from or any number in between 95-90 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 10-15 wt % and a water-miscible organic solventin a range from or any number in between 90-85 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 15-20 wt % and a water-miscible organic solventin a range from or any number in between 85-80 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 20-25 wt % and a water-miscible organic solventin a range from or any number in between 80-75 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 25-30 wt % and a water-miscible organic solventin a range from or any number in between 75-70 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 30-35 wt % and a water-miscible organic solventin a range from or any number in between 70-65 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 35-40 wt % and a water-miscible organic solventin a range from or any number in between 65-60 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 40-45 wt % and a water-miscible organic solventin a range from or any number in between 60-55 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 45-50 wt % and a water-miscible organic solventin a range from or any number in between 65-50 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 50-55 wt % and a water-miscible organic solventin a range from or any number in between 50-45 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 55-60 wt % and a water-miscible organic solventin a range from or any number in between 45-40 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 60-65 wt % and a water-miscible organic solventin a range from or any number in between 40-35 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 65-70 wt % and a water-miscible organic solventin a range from or any number in between 35-30 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 70-75 wt % and a water-miscible organic solventin a range from or any number in between 30-25 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 75-80 wt % and a water-miscible organic solventin a range from or any number in between 25-20 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 80-85 wt % and a water-miscible organic solventin a range from or any number in between 20-15 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 85-90 wt % and a water-miscible organic solventin a range from or any number in between 15-10 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 90-95 wt % and a water-miscible organic solventin a range from or any number in between 10-5 wt %. In some embodiments,the multi-component solvent comprises water in a range from or anynumber in between 95-99 wt % and a water-miscible organic solvent in arange from or any number in between 5-1 wt %.

More typically, the volume ratio of water to water-miscible organicsolvent is typically in the range of from or any number in between 1:6to 6:1 (v:v). In some embodiments, the volume ratio is from or anynumber in between 1:4 to 4:1 (v:v). In some embodiments, the volumeratio is from or any number in between 1:4 to 3:1 (v:v)water:water-miscible organic solvent. In other embodiments, the volumeratio is from or any number in between 1:4 to 1:3 (v:v) water:watermiscible organic solvent. In certain embodiments, the volume ratio is1:1 (v:v) water:water-miscible organic solvent.

Crystallization can be initiated using either temperature reduction(cooling) or solvent removal methods described above. When temperaturereduction is used to initiate crystallization, the temperature of thecrystallization solution is typically reduced from a first temperaturethat is typically in the range of from or any number in between 60° C.to 220° C., such as e.g., 60, 70, 80, 90, 100, 110, 120, 130, 140, 150,160, 180, 190, 200, 210, or 220° C. or within a range defined by any twoof the aforementioned temperatures. When water is a component of thecrystallization solvent, the first temperature is often at the upper endof this range, e.g., in the range of from or any number in between 100°C. to 220° C. or in the range of from or any number in between 150° C.to 220° C. such as e.g., 100, 110, 120, 130, 140, 150, 160, 180, 190,200, 210, or 220° C. or within a range defined by any two of theaforementioned temperatures. In some embodiments, the first temperatureis in the range of from or any number in between 60° C. to 180° C., suchas e.g., 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 180° C.or within a range defined by any two of the aforementioned temperaturesto a second temperature that is lower than the first temperature. Inother embodiments, the first temperature is in the range of from or anynumber in between 70° C. to 150° C., such as e.g., 70, 80, 90, 100, 110,120, 130, 140, or 150° C. or within a range defined by any two of theaforementioned temperatures. When the crystallization solution iscooled, it is typically cooled to a second temperature that is below 60°C., such as e.g., equal to or less than 60, 50, 40, 30, 20, 10, 5, or 0°C. or within a range defined by any two of the aforementionedtemperatures. More typically, it is cooled to a second temperature below50° C. or below 40° C. such as, e.g., equal to or less than 50, 40, 30,20, 10, 5, or 0° C. or within a range defined by any two of theaforementioned temperatures.

Crystallization can also be initiated by removing a first portion of thecrystallization solvent from the crystallization solution to produce anFDCA pathway product slurry, wherein the FDCA pathway product slurrycomprises a first plurality of FDCA pathway product crystals ofdifferent particle sizes and a second portion of the crystallizationsolvent; and separating the plurality of FDCA pathway product crystalsfrom the second portion of the first crystallization solvent. The firstplurality of FDCA pathway product crystals may be optionally dissolvedin the same or different crystallization solvent, and the processrepeated to obtain a second plurality of FDCA pathway product crystalsof different particle sizes.

Seed crystals of the FDCA pathway product may be added to furtherpromote the initiation of crystallization. Other additives, such asanti-foaming agents or crystallization aids, may be added to thecrystallization solution to promote the crystallization process, andenable the formation of a suspension containing FDCA crystals.Anti-foaming agents that are suitable for use in the practice of thepresent disclosure include, for example, silicones, surfactants,phosphates, alcohols, glycols, stearates and the like. Additives such assurfactants or electrolyte polymers may also influence the morphologyand composition of the crystals formed. See, e.g., U.S. Pat. Nos.5,296,639 and 6,534,680, which are incorporated herein by reference intheir entireties. Other additives may function as a flow improver toprevent agglomeration of the crystalline product on storage (see forexample U.S. Pat. No. 6,534,680).

FDCA pathway product crystals produced by the processes described hereincan be separated from the solution (mother liquor) by centrifugation,filtration, or other suitable process for separating solids fromliquids. The crystals can then be washed and dried using any suitableprocess known to those having ordinary skill in the art.

The crystallization processes described herein can be carried out aspart of an integrated process for preparing FDCA pathway productcrystals from a raw feed that comprises the FDCA pathway product. Theset of process steps can be carried out in at least a firstcrystallization zone, a dissolution zone, and a second (refined)crystallization zone. The crystallization processes can also be carriedout as part of an integrated process for preparing FDCA pathway productcrystals from an oxidation feedstock comprising the furanic oxidationsubstrate and the oxidation solvent. In this process, the integratedcrystallization process is further integrated with the oxidationreaction processes described herein. In this integrated process,effluent from at least one oxidation reaction zone is passed, asfeedstock, into the integrated crystallization process. In thecrystallization processes described herein, crystal separationoperations (such as the use of a centrifuge) may optionally be deployedafter each crystallization zone (for example between the crystallizationzone and the next dissolution zone). Illustrative integrated processesfor producing a crystalline FDCA preparation are depicted in FIGS. 6-9.

When the oxidation reaction zone product stream comprises amulti-component solvent that comprises water and a light organicsolvent, the integrated process shown in FIG. 6 may be used. Thisprocess utilizes a solvent switch to water in the second (refined)crystallization zone. In this integrated process, an oxidation zoneproduct stream 105 comprising water, a light organic solvent, and FDCAis passed into a first crystallization zone 200, to produce a solidcrude FDCA crystal product stream 205, a water/light organic solventvapor recycle stream 211 that is optionally recycled to an oxidationreaction zone, and a liquid water/light organic solvent recycle stream207 that is also optionally recycled to an oxidation reaction zone. Anoptional purge stream 209 may be used to remove impurities from theliquid recycle stream 207. Solid crude FDCA crystal product stream 205is fed into a dissolution zone 220 where solid crude FDCA crystalproduct is redissolved. Water 115 is fed into the solid crude FDCAcrystal product stream 205 prior to passage of the latter into thedissolution zone 220 to produce a dissolution zone product stream 225comprising solubilized FDCA in water. Dissolution zone product stream225 is passed into a second (refined) crystallization zone 230 toproduce a water vapor recycle stream 222, a liquid water recycle stream236, and a refined crystallization product stream 235 that comprisesrefined FDCA crystals. Water vapor and liquid water recycle streams, 222and 236, respectively, are both optionally fed into the solid crude FDCAcrystal product stream 205.

When the oxidation reaction zone product stream comprises amulti-component solvent that comprises water and a light organicsolvent, the integrated process shown in FIG. 7 may be used. In thisintegrated process, an oxidation zone product stream 105 comprisingwater, a light organic solvent, and FDCA is passed into a firstcrystallization zone 200, to produce crude FDCA crystal product stream205, a water/light organic solvent vapor recycle stream 213 that is fedinto the solid crude FDCA crystal product stream 205; and a water/lightorganic solvent liquid recycle stream 207 that is optionally recycled toan upstream oxidation reaction zone. An optional purge stream 209 may beused to remove impurities from the liquid recycle stream 207. Crude FDCAcrystal product stream 205 is fed into a dissolution zone 220 wheresolid crude FDCA crystal product is redissolved. Make-up co-solvent(which may be water, the organic light solvent, or a solvent compositioncomprising both water and the light organic solvent) stream 125 is fedinto the solid crude FDCA crystal product stream 205 prior to passage ofthe latter into the dissolution zone 220 to produce a dissolution zoneproduct stream 226 comprising solubilized FDCA in the multi-componentsolvent. Dissolution zone product stream 226 is passed into a second(refined) crystallization zone 230 to produce a co-solvent vapor recyclestream 237, and a refined crystallization product stream 235 thatcomprises refined FDCA crystals. Co-solvent vapor recycle stream 237 isoptionally recycled to the oxidation reaction zone. Co-solvent liquidrecycle stream 233 is optionally fed into the solid crude FDCA crystalproduct stream 205.

In a further integrated process, when the oxidation reaction zoneproduct stream comprises a multi-component solvent that comprises waterand a heavy organic solvent, the process depicted in FIG. 8 may be used.This process utilizes a solvent switch to water in the second (refined)crystallization zone. In this integrated process, an oxidation zoneproduct stream 105 comprising water, a heavy organic solvent, and FDCAis passed into a first crystallization zone 200, to produce a solidcrude FDCA crystal product stream 205, a water vapor recycle stream 212that is optionally recycled to an oxidation reaction zone, and a liquidwater/heavy organic solvent recycle stream 207 that is also optionallyrecycled to an oxidation reaction zone. An optional purge stream 209 maybe used to remove impurities from the liquid recycle stream 207. Solidcrude FDCA crystal product stream 205 is fed into a dissolution zone 220where solid crude FDCA crystal product is redissolved. Water stream 115is fed into the solid crude FDCA crystal product stream 205 prior topassage of the latter into the dissolution zone 220 to produce adissolution zone product stream 223 comprising solubilized FDCA inwater. Dissolution zone product stream 223 is passed into a second(refined) crystallization zone 230 to produce a water vapor recyclestream 245, a liquid water recycle stream 236, and a refinedcrystallization product stream 235 that comprises refined FDCA crystals.Water vapor and liquid water recycle streams, 245 and 236, respectively,are both optionally fed into the solid crude FDCA crystal product stream205.

When the oxidation reaction zone product stream comprises amulti-component solvent (i.e., co-solvent) that comprises water and aheavy organic solvent, the integrated process shown in FIG. 9 may beused. In this integrated process, an oxidation zone product stream 105comprising water, a heavy organic solvent, and FDCA is passed into afirst crystallization zone 200, to produce a solid crude FDCA crystalproduct stream 205, a water vapor recycle stream 211 that is optionallypassed into the solid crude FDCA crystal product stream 205, and aliquid water/heavy organic solvent recycle stream 207 that is optionallyrecycled upstream to an oxidation reaction zone. An optional purgestream 209 may be used to remove impurities from the liquid recyclestream 207. Solid crude FDCA crystal product stream 205 is fed into adissolution zone 220 where solid crude FDCA crystal product isredissolved. Make up solvent stream 125 comprising water and heavyorganic solvent is fed into the solid crude FDCA crystal product stream205 prior to passage of the latter into the dissolution zone 220 toproduce a dissolution zone product stream 223 comprising solubilizedFDCA in water and heavy organic solvent. Dissolution zone product stream223 is passed into a second (refined) crystallization zone 230 toproduce a water vapor recycle stream 245, a liquid water/heavy organicsolvent recycle stream 236, and a refined crystallization product stream235 that comprises refined FDCA crystals. Water vapor stream 245 isoptionally recycled upstream to an oxidation reaction zone. Liquidwater/heavy organic solvent recycle stream 236 is optionally recycled tothe solid crude FDCA crystal product stream 205. An optional purgestream 239 may be used to remove impurities from stream 236. Theprocesses described herein are illustrative and variations to theprocesses are possible (e.g., process streams may be re-routed toalternative points in the processes) The crystalline product produced bythe processes described herein exhibit desirable bulk properties. Thus,in a further embodiment, the present disclosure provides a crystallineFDCA composition comprising a plurality of FDCA crystals characterizedby a distribution of particle sizes, wherein the distribution has a D50in the range of from 50 μm up to 5000 μm. The crystalline FDCApreparation can be produced using the methods described above.

As used herein, the term “D50” refers to the median diameter of theparticle size distribution. In some embodiments, the D50 is in the rangeof from or any number in between 50 μm to 2000 μm, or in the range offrom or any number in between 100 μm to 3500 μm, and often in the rangeof from or any number in between 100 μm to 3000 μm. Typically the D50 ofthe particle size distribution is in the range of from or any number inbetween 100 μm to 750 μm, and more typically, the D50 in the range offrom or any number in between 125 μm to 500 μm, and sometimes in therange of from or any number in between 125 μm to 450 μm, or from or anynumber in between 125 μm to 400 μm, and in some embodiments, in therange of from or any number in between 200 μm to 500 μm.

In some embodiments of the above, the crystalline FDCA preparationcomprises less than 1 weight % FDCA crystals having a particle size lessthan 10 μm. In other embodiments, the crystalline FDCA preparationcomprises less than 10 wt %, and more typically less than 9 wt %, lessthan 8 wt %, less than 7 wt %, less than 6 wt %, or less than 5 wt %FDCA crystals having a particle size less than 10 μm. In furtherembodiments, the crystalline FDCA preparations of the present disclosuretypically comprise less than 10 wt %, less than 9 wt %, less than 8 wt%, less than 7 wt %, less than 6 wt %, less than 5 wt %, less than 4 wt%, less than 3 wt %, less than 2 wt %, or less than 1 wt % FDCA crystalshaving a particle size less than 4 μm.

Typically, the crystalline FDCA preparation comprises at least 98 wt %FDCA, and more typically, it comprises at least 99 wt % FDCA, and insome embodiments, it comprises greater than 99 wt % FDCA.

The crystallization processes of the present disclosure may be carriedout using known industrial crystallizer systems that are suitable forcarrying out solution phase crystallizations. Suitable systems includefor example, batch crystallizers, continuous crystallizers (e.g., forcedcirculation crystallizers, draft-tube crystallizers, draft-tube-baffledcrystallizers, or Oslo-type crystallizers, and the like), and other suchcrystallizer systems.

The crystalline FDCA preparations of the present disclosure aretypically dry, and comprise less than 1 wt % water. Often, they compriseless than 0.9 wt %, or less than 0.8 wt %, or less than 0.7 wt %, orless than 0.6 wt %, or less than 0.5 wt %, or less than 0.4 wt %, orless than 0.3 wt %, or less than 0.2 wt % water or an amount of waterthat is within a range defined by any two of the aforementioned amounts.

In a further embodiment, the present disclosure provides a compositioncomprising FDCA and a multi-component solvent, wherein themulti-component solvent comprises water and a water-miscible aproticorganic solvent, and wherein the FDCA is present at a concentration ofat least 5 wt %. In some embodiments, the FDCA is present at aconcentration of at least 6 wt %, or at least 7 wt %, or at least 8 wt%, or at least 9 wt %, or at least 10 wt %, or at least 11 wt %, or atleast 12 wt %, or at least 13 wt %, or at least 14 wt %, or at least 15wt %. The composition comprising FDCA and a multi-component solvent canbe a solution. The solution can contain FDCA that is solubilized suchthat the solution does not contain FDCA solids. The compositioncomprising FDCA and a multi-component solvent can be a solution (suchthat the solution does not contain FDCA solids) at room temperature orat a temperature up to 160° C. (such as e.g., 20, 30, 40, 50, 60, 70,80, 90, 100, 110, 120, 130, 140, 150, or 160° C. or within a rangedefined by any two of the aforementioned temperatures). Thesecompositions are useful in carrying out various unit operations thatoccur downstream of the oxidation step, including, for example,transesterification, polycondensation, or crystallization, and otherdownstream processes involved in the production of FDCA-based products.Typically, the water-miscible aprotic organic solvent is NMP or anether, such as, for example, a glyme or dioxane.

In some embodiments, the water-miscible aprotic organic solvent speciesis at least 5 vol %, at least 10 vol %, at least 15 vol %, at least 20vol %, at least 25 vol %, at least 30 vol %, at least 35 vol %, at least40 vol %, at least 45 vol %, at least 50 vol %, at least 55 vol %, atleast 60 vol %, at least 65 vol %, at least 70 vol %, at least 75 vol %,at least 80 vol %, at least 85 vol %, at least 90 vol %, or at least 95vol % of the multi-component solvent system; and correspondingly, wateris typically less than 95 vol %, less than 90 vol %, less than 85 vol %,less than 80 vol %, less than 75 vol %, less than 70 vol %, less than 65vol %, less than 60 vol %, less than 55 vol %, less than 50 vol %, lessthan 45 vol %, less than 40 vol %, less than 35 vol %, less than 30 vol%, less than 25 vol %, less than 20 vol %, less than 15 vol %, less than10 vol %, or less than 5 vol %, respectively, of the multi-componentsolvent or within a range defined by any two of the aforementionedamounts.

More typically, the volume ratio of water to water-miscible aproticorganic solvent is typically in the range of from 1:6 to 6:1. In someembodiments, the volume ratio is from 1:4 to 4:1 (v:v) or from 1:4 to3:1 (v:v) water:water-miscible aprotic organic solvent In certainembodiments, the volume ratio is 1:1 (v:v) water:water-miscible aproticorganic solvent.

II. Catalyst Preparation

Heterogeneous oxidation catalysts employed in the processes describedherein may be prepared by any one of a number of methods. For example,noble metals can be deposited onto the exterior and interior surfaces ofthe support material using methods such as, for example, incipientwetness, ion exchange, deposition-precipitation, and/or vacuumimpregnation. When more than one metal is deposited onto the support,they may be deposited sequentially or simultaneously. After depositingthe metals onto the surfaces of the catalyst support, the catalyst istypically dried at a temperature in the range of 20° C. to 120° C. (suchas e.g., 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, or 120° C. or withina range defined by any two of the aforementioned temperatures for aperiod of time that is in the range of from one hour up to twenty fourhours e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, 21, 22, 23, or 24 hours or within a range defined by any twoof the aforementioned time periods. The catalyst can be dried undersub-atmospheric pressure conditions. In some embodiments, the catalystis reduced after drying (e.g., by flowing 5% H₂ in N₂ at a temperatureof at least 200° C. for a period of time (e.g., at least three hours).The catalyst may also be calcined in air at a temperature of at least200° C. for a period of time of at least three hours.

When the heterogeneous oxidation catalyst comprises gold, the gold maybe added to the support material as a solubilized constituent in aliquid. When the gold-liquid solution is mixed with the supportmaterial, a suspension of support material in the solubilizedgold-containing liquid phase is formed. In this method, a base is thenadded to the suspension in order to form a precipitant of insoluble goldcomplex which deposits on the surfaces of the support material in auniform fashion. In this deposition method, the solubilized goldconstituent may be in the form of a gold salt (e.g., HAuCl₄, and thelike). Although any base that can promote the formation of the insolublegold complex is suitable, bases such as potassium hydroxide (KOH) andsodium hydroxide (NaOH), are typically employed. The resulting solidsmay be collected by known methods for separating solids from liquids,including, for example, filtration, centrifugation, and the like. Thecollected solids may be optionally washed, then optionally heated todry. Heating may also be employed to reduce the gold complex on thesupport to gold (0). Heating may be conducted at temperatures in therange of from 60° C. to dry, and from 150° C. for reduction up to 500°C., at which temperature the gold can be effectively reduced (such ase.g., 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 180, 190, 200,210, 220, 230, 240, 250, 300, 350, 400, 450, or 500° C. or within arange defined by any two of the aforementioned temperatures). In variousembodiments, the heating step may be conducted in the presence of areducing atmosphere in order to promote the reduction of the complex todeposit the gold onto the support as gold (0). The duration of heatingmay vary from a few hours to a few days depending on various factors,including, for example, the objective of the heating step and thedecomposition rate of the base which is added to form the insolublecomplex. Typically, the heating time for the purpose of drying is in therange of from 2 to 24 hours (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 hours or within arange defined by any two of the aforementioned time periods), and forreducing the gold complex, in the range of from 1 to 4 hours (e.g., 1,2, 3, or 4 hours or within a range defined by any two of theaforementioned time periods).

When the heterogeneous oxidation catalyst comprises platinum, theplatinum is typically added to the support material by contacting thesupport material with a solution containing a soluble platinum precursorcompound or with a platinum-containing colloid. Platinum may bedeposited on the support material in the form of any one of a variety ofcompounds, such as, for example, platinum (II) nitrate, platinum (IV)nitrate, platinum oxynitrate, platinum (II) acetylacetonate (acac),tetraamineplatinum (II) nitrate, tetraamineplatinum (II)hydrogenphosphate, tetraamineplatinum (II) nitrate, tetraamineplatinum(II) hydrogenphosphate, tetraamineplatinum (II) nitrate,tetraamineplatinum (II) hydrogenphosphate, tetraamineplatinum (II)hydrogencarbonate, tetraamineplatinum (II) hydroxide, H₂PtCl₆, PtCl₄,Na₂PtCl₄, K₂PtCl₄, (NH₄)₂PtCl₄, Pt(NH₃)₄Cl₂, mixed Pt(NH₂)_(x)Cl_(y),K₂Pt(OH)₆, Na₂Pt(OH)₆, (NMe₄)₂Pt(OH)₆, and [(C₂H₇NO)₂]Pt(OH)₆, and thelike. Typically, platinum is added to the support material as platinum(II) nitrate, platinum (IV) nitrate, platinum (II) acetylacetonate(acac), tetraamine platinum (II) hydroxide, K₂PtCl₄, or K₂Pt(OH)₆.

If a gold- and platinum-containing heterogeneous oxidation catalyst isdesired, the platinum can be deposited onto the surfaces of the supportmaterial either before or after gold has been deposited, oralternatively, the platinum and gold can be deposited together. Whenplatinum is added to a gold-containing heterogeneous oxidation catalyst,it can be added after deposition of the gold, and either before or afterdrying or after drying, and before or after reduction of the gold. Whenplatinum is added to the catalyst support prior to the deposition ofgold, the platinum employed is one which will not be re-dissolved uponaddition of the base used to promote the deposition of gold onto thesupport.

After the platinum compound is added to the support material, theresulting platinum-containing support material is dried. Drying may beconducted at room temperature or at a temperature up to 120° C. (such ase.g., 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, or 120, ° C. or within arange defined by any two of the aforementioned temperatures. Typically,drying is conducted at a temperature in the range of or any number inbetween 40° C. to 80° C., and often at a temperature of 60° C. (such ase.g., 40, 50, 60, 70, or 80° C. or within a range defined by any two ofthe aforementioned temperatures. Drying typically proceeds over a periodof time in the range of from a few minutes to a few hours. Typically,the platinum-containing support material is dried over a period of timein the range of from or any number in between 6 hours to 24 hours (e.g.,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or24 hours or within a range defined by any two of the aforementioned timeperiods). The drying can be conducted with a continuous or a stagedtemperature increase of from or any number in between 60° C. to 120° C.(such as e.g., 60, 70, 80, 90, 100, 110, or 120, ° C. or within a rangedefined by any two of the aforementioned temperatures) on a bandcalciner or belt dryer.

After drying the platinum-containing support material, the material issubjected to at least one thermal treatment in order to reduce theplatinum (which is deposited as platinum (II) or platinum (IV)) toplatinum (0). In certain embodiments, the thermal treatment(s) may beconducted under a forming gas atmosphere. Alternatively, a liquidreducing agent may be employed to reduce the platinum. For example,hydrazine or formaldehyde or formic acid or a salt thereof (e.g., sodiumformate) or NaH₂PO₂ may be employed to effect the reduction of platinum.

The temperature(s) at which the thermal treatment(s) is (are) typicallyconducted in the range of from or any number in between 150° C. to 600°C. (such as e.g., 150, 200, 250, 300, 350, 400, 450, 500, 550, or 600°C. or within a range defined by any two of the aforementionedtemperatures). In some embodiments, the temperatures of the thermaltreatment(s) is (are) in the range of from or any number in between 200°C. to 500° C., and, more typically, in the range of from or any numberin between 200° C. to 400° C. (such as e.g., 200, 250, 300, 350, or 400°C. or within a range defined by any two of the aforementionedtemperatures). The thermal treatment is typically conducted for a periodof time in the range of from or any number in between 1 hour to 8 hoursor in some embodiments, in the range of from or any number in between 1hour to 3 hours (e.g., 1, 2, 3, 4, 5, 6, 7, or 8 or within a rangedefined by any two of the aforementioned time periods).

III. Preparation of FDCA Derivatives and FDCA Polymers

Derivatives of FDCA can be readily prepared from the FDCA produced usingthe processes of the present disclosure. For example, in someembodiments, it may be desirable to further convert the FDCA pathwayproduct(s) to an FDCA salt (e.g., by adding a base, such as, forexample, sodium hydroxide, potassium hydroxide, sodium hydroxide,ammonia, and the like), an ester, an amide, a halide, and the like.

The dicarboxylic acid functionality of the FDCA makes it useful as amonomer, either as is or in derivatized form. FDCA derivatives that areuseful as monomers for further polymerization, include FDCA esters, FDCAamides, FDCA halides, and the like. The resulting FDCA derivatives maybe optionally purified by, for example, distillation, crystallization,and the like.

In one embodiment, the present disclosure provides a process forconverting the FDCA to an ester of FDCA, the converting step comprisingcontacting the FDCA produced by the processes of the present disclosurewith an alcohol under conditions sufficient to produce a correspondingFDCA monoester or FDCA diester. Alcohols suitable for use in thepractice of the present disclosure include branched or unbranched,C₁-C₂₀ alcohols (e.g., aliphatic alcohols or aromatic C₅-C₂₀ alcoholsand including, for example, diols or polyols). In some embodiments, thealcohol is a branched or unbranched, C₁-C₁₀ alcohol, C₁-C₆ alcohol, or abranched or unbranched, C₁-C₄ (i.e., methyl alcohol, ethyl alcohol,n-propyl alcohol, iso-propyl alcohol, 2-methylpropan-1-ol (i.e.,isobutyl alcohol), 2-methyl-2-propanol (i.e., t-butyl alcohol), orn-butyl, and the like. C₁-C₁₂ polyols, including diols and otherpolyols, are also suitable for use in these processes. These include,for example, ethanediol (ethylene glycol), 1,3-propanediol,1,4-butanediol, 2,3-butanediol, a hexanediol (e.g., 1,6-hexanediol,1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, and the like), ahexanetriol (e.g., 1,2,6-hexanetriol, 1,2,3-hexanetriol,1,3,6-hexanetriol, and the like), bis(hydroxymethyl)benzene,1,8-octanediol, 4-octene-1,8-diol, 1,9-nonanediol, 2-nonene-1,4-diol,7-nonene-1,5-diol, 7-nonene-1,5-diol, 1,10-decanediol, or1,12-dodecanediol, and the like, as well as any combination thereof.Conditions sufficient for promoting the formation of a mono- or di-esterof FDCA (i.e., “esterifying conditions”) include, for example,contacting the FDCA with the desired alcohol in the presence of acatalyst, such as, for example, a mineral acid (such as, for example,HCl, or H₂SO₄, and the like) at a temperature in the range of from 50°C. to 150° C. (such as e.g., 50, 60, 70, 80, 90, 100, 110, 120, 130,140, or 150° C. or within a range defined by any two of theaforementioned temperatures). Often, the alcohol is methanol and theester of FDCA is the methyl ester of FDCA, and typically, it is thedimethyl ester of FDCA. In other embodiments, the alcohol is ethanol,and the ester of FDCA is the ethyl ester of FDCA, and typically, it isthe diethyl ester of FDCA.

An illustrative integrated process for producing purified dimethyl esterof FDCA by distillation is provided in FIG. 10. With reference to FIG.10, a solid crude FDCA feedstock stream 205 is mixed with a methanolstream 250 and optionally a methanol/water vapor stream 265 prior tobeing passed into an esterification zone 280 where FDCA and methanol aresubjected to conditions that promote esterification to produce anesterification zone product stream 285, which comprises the dimethylester of FDCA. Esterification zone product stream 285 is passed into aflash distillation zone, which comprises a flash distillation column, toproduce a methanol/water vapor recycle stream 265 and a flash zoneproduct stream 263 which comprises the dimethyl ester of FDCA. A portionof the water produced in the esterification zone may be removed from themethanol/water vapor recycle stream 265 in a water vapor purge stream267. The methanol or methanol/water vapor recycle stream 265 is recycledto the FDCA feedstock stream 205. The flash zone product stream 263 ispassed into a distillation column zone 270 to product an impurity stream273 and a light stream 275 comprising purified dimethyl ester of FDCA.

An alternative integrated process for producing purified dimethyl esterof FDCA that utilizes crystallization as the purification step isprovided in FIG. 11. In this process, a solid crude FDCA feedstockstream 205 is mixed with a methanol make up stream 265 and optionally avapor methanol/water stream 297 and subsequently passed into anesterification zone 280 where FDCA and methanol are subjected toconditions that promote esterification to produce an esterification zoneproduct stream 285, which comprises the dimethyl ester of FDCA.Esterificaton zone product stream 285 is passed into a diestercrystallizer zone 290, to produce a diester crystallizer zone productstream 295 that comprises the dimethyl ester of FDCA in crystallineform, a liquid recycle stream 293 that comprises methanol and water, anda vapor methanol/water stream 297. Liquid recycle stream 293 is passedinto the vapor methanol/water stream 297. A portion of the water in thevapor methanol/water stream 297 may be removed in a water vapor purgestream 281. Optional purge stream 294 facilitates removal of impuritycomponents from the vapor methanol/water stream 293.

In a another embodiment, the present disclosure provides a process forconverting the FDCA or an FDCA ester to an FDCA amide, wherein theconverting step comprises contacting the FDCA or FDCA ester produced bythe processes of the present disclosure with an amino-substitutedcompound under conditions sufficient to produce a corresponding FDCAmono-amide or FDCA diamide. Conditions sufficient for promoting theformation of the mono- or di-amide of FDCA (i.e., amidation conditions”)include, for example, contacting the FDCA or FDCA ester with the amineunder conditions that are known to convert carboxylic acids or estersinto amides. See, e.g., March's Advanced Organic Chemistry Eds. M. B.Smith and J. March; Wiley (2013), which is incorporated herein byreference. Amino-substituted compounds suitable for use in the practiceof the present disclosure include, for example, C₁-C₂₀ aliphatic oraromatic amines. Typically, the amino-substituted compound is a C₁-C₁₀,or C₁-C₆ mono- or di-amine. Suitable amino-substituted compoundsinclude, for example, 1,6-hexamethylenediamine,1,5-pentamethylenediamine or 1,4-tetramethylenediamine, and the like.

In a further embodiment, the present disclosure provides a process forconverting the FDCA to an FDCA halide, the converting step comprisingcontacting the FDCA produced by the processes of the present disclosurewith a halogenating agent (e.g. SOCl₂) under conditions that are knownto convert carboxylic acids into acyl halides. See for example March'sAdvanced Organic Chemistry Eds. M. B. Smith and J. March; Wiley (2013),which is incorporated herein by reference in its entirety.

Certain FDCA derivatives may be employed as FDCA-monomers, which areuseful for producing polymers, such as, for example, polyesters,polyamides, and the like. As used herein, the term “FDCA-based monomers”refers to FDCA, as well as FDCA derivatives that have the ability toreact with other monomers to form a polymer. Thus, in a furtherembodiment, the present disclosure provides a process for producing anFDCA-based polymer, the method comprising polymerizing an FDCA-basedmonomer of the present disclosure under conditions sufficient to producethe FDCA-based polymer. In some embodiments, the FDCA-based monomer isan FDCA derivative selected from the group consisting of an FDCA ester(i.e., a monoester or diester), an FDCA amide (i.e., an FDCA monoamideor an FDCA diamide), and an FDCA halide (e.g., an FDCA monochloride, anFDCA dichloride, and the like), and the like. In certain embodiments,the FDCA-based monomer is polymerized with a second monomer that is notthe same as the first monomer. Second monomers that are suitable for usein the practice of the present disclosure include a polyol that has atleast two hydroxyl groups.

Exemplary polyols that can be used as a suitable co-monomer includeethanediol (ethylene glycol), 1,3-propanediol, 1,4-butanediol,2,3-butanediol, a hexanediol (e.g., 1,6-hexanediol, 1,2-hexanediol,1,5-hexanediol, 2,5-hexanediol, and the like), a hexanetriol (e.g.,1,2,6-hexanetriol, 1,2,3-hexanetriol, 1,3,6-hexanetriol, and the like),bis(hydroxymethyl)benzene, 1,8-octanediol, 4-octene-1,8-diol,1,9-nonanediol, 2-nonene-1,4-diol, 7-nonene-1,5-diol, 7-nonene-1,5-diol,1,10-decanediol, or 1,12-dodecanediol, and the like, as well as anycombination thereof. Typically, the polyol is a diol. Exemplarydicarboxylic acids include, for example, succinic acid, or adipic acid,and the like. Exemplary hydroxyacids include, for example, lactic acid,succinic acid, malic acid, salicylic acid, syringic acid, or ferulicacid, and the like. Exemplary sugar alcohols include, for example,isosorbide, isomannide, or isoidide, and the like. Typically, theFDCA-based monomer is selected from the group consisting of FDCA anddimethyl FDCA ester and a second monomer is employed that is a polyol.

When the FDCA-based monomer is FDCA, the second monomer can be analiphatic or aromatic diamine or an aliphatic or aromatic polyol (e.g.,a diol, or a triol, and the like). Suitable diamines include, forexample, 1,6-hexamethylenediamine, 1,5-pentamethylenediamine, or1,4-tetramethylenediamine, and the like. Suitable polyols include thosedescribed above.

The FDCA-based polymers of the present disclosure are typically producedusing a polycondensation reaction, either in a solution polymerizationor melt polymerization. In some embodiments, the polymerization step ispreceded by a transesterification step. The polycondensation reactionsare typically carried out in the presence of a catalyst, such as, forexample, dibutyltin (IV) oxide, titanium (IV) isopropoxide, antimony(III) oxide (see, e.g., G.-J. M. Gruter, et al., Comb. Chem. HighThroughput Screening (2012) 15:180-188, which is incorporated herein byreference.

In a specific embodiment, the present disclosure provides a method forproducing an FDCA-based polyester, the method comprising contacting anFDCA-monomer selected from the group consisting of FDCA and FDCAdimethyl ester with a C₁-C₂₀ polyol at a temperature in the range offrom 120° C. to 225° C. (such as e.g., 120, 130, 140, 150, 160, 180,190, 200, 210, or 225° C. or within a range defined by any two of theaforementioned temperatures) to form a reaction mixture for producingthe corresponding dihydroxy C₁-C₂₀ FDCA ester (in an esterification ortransesterification step, respectively), then increasing the temperatureof the reaction mixture to a temperature in the range of from 180° C. to250° C. (such as e.g., 180, 190, 200, 210, 220, 230, 240, or 250° C. orwithin a range defined by any two of the aforementioned temperatures) toproduce the corresponding FDCA-based polyester (in a polycondensationstep). Typically, the C₁-C₂₀ FDCA polyol is a diol selected from thegroup consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol,2,3-butanediol, and 1,6-hexanediol. In certain embodiments the molecularweight of the resultant polyester can be further increased by a thirdstage solid state polymerization in which the polymeric material (in theform of pellets, granules, flakes or chips and the like) is subjected toa certain amount of time, such as 1-24 hours (e.g., 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24hours or within a range defined by any two of the aforementioned timeperiods)) at elevated temperatures above the glass transitiontemperature and below the melting temperature of the polyester. Thepolycondensation methods are typically conducted at pressures below 1atmosphere.

IV. Production of Furanic Oxidation Substrate

While furanic oxidation substrate material can be readily purchased, itmay be desirable in certain circumstances to produce the furanicoxidation substrate. The present disclosure provides a process forproducing a furanic oxidation substrate, the process comprising:

(a^(o)) contacting a carbohydrate feedstock comprising a sugar and adehydration solvent with a catalyst under conditions sufficient to forma (dehydration) reaction mixture for dehydrating the sugar to producethe furanic oxidation substrate (referred to herein as the “dehydrationprocess”). Typically, the sugar is a hexose, such as, for example,glucose, galactose, mannose, idose, a ketohexose, fructose, levulose,sorbose, tagatose, or allose, and the like. Usually, the sugar isglucose or fructose. Often, the sugar is fructose.

The term “dehydration solvent” refers to a solvent in which both thesugar and the furanic oxidation substrate are each separately soluble ata minimum level of at least 2% by weight at the temperature at which thedehydration reaction is carried out. Typically, the dehydration solventis one in which the furanic oxidation substrate has a solubility of atleast 3 wt %, at least 4 wt %, at least 5 wt %, at least 6 wt %, atleast 7 wt %, at least 8 wt %, at least 9 wt %, at least 10 wt %, atleast 11 wt %, at least 12 wt %, at least 13 wt %, at least 14 wt %, atleast 15 wt %, at least 17%, at least 19%, at least 21%, at least 23%,or at least 25% as measured at the temperature at which the dehydrationreaction is carried out. In some embodiments, the concentration offuranic oxidation substrate in the dehydration solvent ranges from orany number in between 2-4 wt %, 3-5 wt %, 4-6 wt %, 5-7 wt %, 6-8 wt %,7-9 wt %, 8-10 wt %, 9-11 wt %, 10-12 wt %, 11-13 wt %, 12-14 wt %,13-15 wt %, 14-16 wt %, 15-17 wt %, 16-18 wt %, 17-19 wt %, 18-20 wt %,19-21 wt %, 20-22 wt %, 21-23 wt %, 22-24 wt %, or 23-25 wt % or withina range defined by any of two of the aforementioned weight percentages.Typically, the dehydration solvent comprises water and/or awater-miscible organic solvent. More typically, the dehydration solventis a multi-component solvent. Usually, the multi-component solventemployed in the dehydration process comprises water and a water-miscibleaprotic organic solvent. Water-miscible aprotic organic solvents andmulti-component solvent compositions that are suitable for use in thedehydration process are the same as those that are suitable for use inthe FDCA pathway product-generating processes as described hereinabove.In some embodiments, the water-miscible aprotic organic solvent isN-Methyl-2-Pyrrolidone (NMP). In some embodiments, the carbohydratefeedstock comprises fructose and the furanic oxidation substratecomprises HMF.

Exemplary water-miscible aprotic solvents suitable for use indehydration solvent include tetrahydrofuran, a glyme, dioxane, adioxolane, dimethylformamide, dimethylsulfoxide, sulfolane, acetone,N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”),gamma-valerolactone, and the like. Preferably, the water-miscibleaprotic organic solvent is an ether, such as, for example, a glyme,dioxane (1,4-dioxane), a dioxolane (e.g., 1,3-dioxolane),tetrahydrofuran, and the like. Glymes that are suitable for use in thepractice of the present disclosure include, for example, monoglyme(1,2-dimethoxyethane, “DME”), ethyl glyme, diglyme (diethylene glycoldimethyl ether), ethyl diglyme, triglyme, butyl diglyme, tetraglyme, apolyglyme, a highly ethoxylated diether of a high molecular weightalcohol (“higlyme”), and the like. Often, the dehydration solvent is amulti-component solvent comprising water and a water-miscible aproticorganic solvent that is glyme, diglyme, or dioxane.

In some embodiments, the water-miscible organic solvent species is atleast 5 volume % (vol %), at least 10 vol %, at least 15 vol %, at least20 vol %, at least 25 vol %, at least 30 vol %, at least 35 vol %, atleast 40 vol %, at least 45 vol %, at least 50 vol %, at least 55 vol %,at least 60 vol %, at least 65 vol %, at least 70 vol %, at least 75 vol%, at least 80 vol %, at least 85 vol %, at least 90 vol %, or at least95 vol % of the multi-component solvent; and correspondingly, water istypically less than 95 vol %, less than 90 vol %, less than 85 vol %,less than 80 vol %, less than 75 vol %, less than 70 vol %, less than 65vol %, less than 60 vol %, less than 55 vol %, less than 50 vol %, lessthan 45 vol %, less than 40 vol %, less than 35 vol %, less than 30 vol%, less than 25 vol %, less than 20 vol %, less than 15 vol %, less than10 vol %, or less than 5 vol %, respectively, of the multi-componentsystem.

In some embodiments, the multi-component solvent comprises water in arange from or any number in between 1-5 wt % and a water-miscibleorganic solvent in a range from or any number in between 99-95 wt %. Insome embodiments, the multi-component solvent comprises water in a rangefrom or any number in between 5-10 wt % and a water-miscible organicsolvent in a range from or any number in between 95-90 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 10-15 wt % and a water-miscible organic solventin a range from or any number in between 90-85 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 15-20 wt % and a water-miscible organic solventin a range from or any number in between 85-80 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 20-25 wt % and a water-miscible organic solventin a range from or any number in between 80-75 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 25-30 wt % and a water-miscible organic solventin a range from or any number in between 75-70 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 30-35 wt % and a water-miscible organic solventin a range from or any number in between 70-65 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 35-40 wt % and a water-miscible organic solventin a range from or any number in between 65-60 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 40-45 wt % and a water-miscible organic solventin a range from or any number in between 60-55 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 45-50 wt % and a water-miscible organic solventin a range from or any number in between 65-50 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 50-55 wt % and a water-miscible organic solventin a range from or any number in between 50-45 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 55-60 wt % and a water-miscible organic solventin a range from or any number in between 45-40 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 60-65 wt % and a water-miscible organic solventin a range from or any number in between 40-35 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 65-70 wt % and a water-miscible organic solventin a range from or any number in between 35-30 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 70-75 wt % and a water-miscible organic solventin a range from or any number in between 30-25 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 75-80 wt % and a water-miscible organic solventin a range from or any number in between 25-20 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 80-85 wt % and a water-miscible organic solventin a range from or any number in between 20-15 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 85-90 wt % and a water-miscible organic solventin a range from or any number in between 15-10 wt %. In someembodiments, the multi-component solvent comprises water in a range fromor any number in between 90-95 wt % and a water-miscible organic solventin a range from or any number in between 10-5 wt %. In some embodiments,the multi-component solvent comprises water in a range from or anynumber in between 95-99 wt % and a water-miscible organic solvent in arange from or any number in between 5-1 wt %.

In some embodiments, the volume ratio of water to water-miscible organicsolvent is in the range from or any number in between 1:6 to 6:1. Incertain embodiments, the volume ratio is from or any number in between1:4 to 4:1 water:water-miscible organic solvent. In other embodiments,the volume ratio is from or any number in between 1:4 to 3:1 water:watermiscible organic solvent. In other embodiments, the volume ratio is fromor any number in between 1:3 to 3:1 water:water miscible organicsolvent. In certain embodiments, the volume ratio is 1:1water:water-miscible organic solvent.

In some embodiments, the multi-component solvent comprises water and twodifferent water-miscible organic solvents. Typically both of thewater-miscible organic solvents are water-miscible aprotic organicsolvents. Each of the two water-miscible aprotic solvents can beindependently selected from the group of tetrahydrofuran, a glyme, adioxane, a dioxolane, dimethylformamide, dimethylsulfoxide, sulfolane,acetone, N-methyl-2-pyrrolidone (“NMP”), methyl ethyl ketone (“MEK”),and gamma-valerolactone. One or both of the water-miscible aproticorganic solvent can be an ether, such as, for example, a glyme, dioxane(for example 1,4-dioxane), dioxolane (e.g., 1,3-dioxolane),tetrahydrofuran, and the like. Glymes include, for example, monoglyme(1,2-dimethoxyethane, “DME”), ethyl glyme, diglyme (diethylene glycoldimethyl ether), ethyl diglyme, triglyme, butyl diglyme, tetraglyme, apolyglyme, a highly ethoxylated diether of a high molecular weightalcohol (“higlyme”), and the like.

In some embodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 1:1:1 (v:v:v). In someembodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 1:2:1 (v:v:v). In someembodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 1:2:2 (v:v:v). In someembodiments, the volume ratio of water to the first and secondwater-miscible organic solvent is approximately 2:1:1 (v:v:v).

In some embodiments, the multi-component solvent for the dehydrationsolvent comprises water and two different water-miscible organicsolvents with the relative amounts of water to the first and secondwater-miscible organic solvents as shown in Table B.

TABLE B Weight percent Weight percent Weight percent of first water- ofsecond water- of water miscible organic miscible organic in multi-solvent in solvent in multi- component multi-component component solventsystem solvent system solvent system 1-5% 90-98% 1-5% 1-5% 85-94%  5-10%1-5% 80-89% 10-15% 1-5% 75-84% 15-20% 1-5% 70-79% 20-25% 1-5% 65-74%25-30% 1-5% 60-69% 30-35% 1-5% 55-64% 35-40% 1-5% 50-59% 40-45% 1-5%45-54% 45-50% 1-5% 40-49% 50-55% 1-5% 35-44% 55-60% 1-5% 30-39% 60-65%1-5% 25-34% 65-70% 1-5% 20-29% 70-75% 1-5% 15-24% 75-80% 1-5% 10-19%80-85% 1-5%  5-14% 85-90% 1-5% 1-9% 90-94%  5-10% 85-94% 1-5%  5-10%80-90%  5-10%  5-10% 75-85% 10-15%  5-10% 70-80% 15-20%  5-10% 65-75%20-25%  5-10% 60-70% 25-30%  5-10% 55-65% 30-35%  5-10% 50-60% 35-40% 5-10% 45-55% 40-45%  5-10% 40-50% 45-50%  5-10% 35-45% 50-55%  5-10%30-40% 55-60%  5-10% 25-35% 60-65%  5-10% 20-30% 65-70%  5-10% 15-25%70-75%  5-10% 10-20% 75-80%  5-10%  5-15% 80-85%  5-10%  1-10% 85-89%10-15% 80-89% 1-5% 10-15% 75-85%  5-10% 10-15% 70-80% 10-15% 10-15%65-75% 15-20% 10-15% 60-70% 20-25% 10-15% 55-65% 25-30% 10-15% 50-60%30-35% 10-15% 45-55% 35-40% 10-15% 40-50% 40-45% 10-15% 35-45% 45-50%10-15% 30-40% 50-55% 10-15% 25-35% 55-60% 10-15% 20-30% 60-65% 10-15%15-25% 65-70% 10-15% 10-20% 70-75% 10-15%  5-15% 75-80% 10-15%  1-10%80-84% 15-20% 75-84% 1-5% 15-20% 70-80%  5-10% 15-20% 65-75% 10-15%15-20% 60-70% 15-20% 15-20% 55-65% 20-25% 15-20% 50-60% 25-30% 15-20%45-55% 30-35% 15-20% 40-50% 35-40% 15-20% 35-45% 40-45% 15-20% 30-40%45-50% 15-20% 25-35% 50-55% 15-20% 20-30% 55-60% 15-20% 15-25% 60-65%15-20% 10-20% 65-70% 15-20%  5-15% 70-75% 15-20%  1-10% 75-79% 20-25%70-79% 1-5% 20-25% 65-75%  5-10% 20-25% 60-70% 10-15% 20-25% 55-65%15-20% 20-25% 50-60% 20-25% 20-25% 45-55% 25-30% 20-25% 40-50% 30-35%20-25% 35-45% 35-40% 20-25% 30-40% 40-45% 20-25% 25-35% 45-50% 20-25%20-30% 50-55% 20-25% 15-25% 55-60% 20-25% 10-20% 60-65% 20-25%  5-15%65-70% 20-25%  1-10% 70-74% 25-30% 65-74% 1-5% 25-30% 60-70%  5-10%25-30% 55-65% 10-15% 25-30% 50-60% 15-20% 25-30% 45-55% 20-25% 25-30%40-50% 25-30% 25-30% 35-45% 30-35% 25-30% 30-40% 35-40% 25-30% 25-35%40-45% 25-30% 20-30% 45-50% 25-30% 15-25% 50-55% 25-30% 10-20% 55-60%25-30%  5-15% 60-65% 25-30%  1-10% 65-69% 30-35% 60-69% 1-5% 30-35%55-65%  5-10% 30-35% 50-60% 10-15% 30-35% 45-55% 15-20% 30-35% 40-50%20-25% 30-35% 35-45% 25-30% 30-35% 30-40% 30-35% 30-35% 25-35% 35-40%30-35% 20-30% 40-45% 30-35% 15-25% 45-50% 30-35% 10-20% 50-55% 30-35% 5-15% 55-60% 30-35%  1-10% 60-64% 35-40% 55-64% 1-5% 35-40% 50-60% 5-10% 35-40% 45-55% 10-15% 35-40% 40-50% 15-20% 35-40% 35-45% 20-25%35-40% 30-40% 25-30% 35-40% 25-35% 30-35% 35-40% 20-30% 35-40% 35-40%15-25% 40-45% 35-40% 10-20% 45-50% 35-40%  5-15% 50-55% 35-40%  1-10%55-59% 40-45% 50-59% 1-5% 40-45% 45-55%  5-10% 40-45% 40-50% 10-15%40-45% 35-45% 15-20% 40-45% 30-40% 20-25% 40-45% 25-35% 25-30% 40-45%20-30% 30-35% 40-45% 15-25% 35-40% 40-45% 10-20% 40-45% 40-45%  5-15%45-50% 40-45%  1-10% 50-54% 45-50% 45-54% 1-5% 45-50% 40-50%  5-10%45-50% 35-45% 10-15% 45-50% 30-40% 15-20% 45-50% 25-35% 20-25% 45-50%20-30% 25-30% 45-50% 15-25% 30-35% 45-50% 10-20% 35-40% 45-50%  5-15%40-45% 45-50%  1-10% 45-49% 50-55% 40-49% 1-5% 50-55% 35-45%  5-10%50-55% 30-40% 10-15% 50-55% 25-35% 15-20% 50-55% 20-30% 20-25% 50-55%15-25% 25-30% 50-55% 10-20% 30-35% 50-55%  5-15% 35-40% 50-55%  1-10%40-44% 55-60% 35-44% 1-5% 55-60% 30-40%  5-10% 55-60% 25-35% 10-15%55-60% 20-30% 15-20% 55-60% 15-25% 20-25% 55-60% 10-20% 25-30% 55-60% 5-15% 30-35% 55-60% 1-10% 35-39% 60-65% 30-39% 1-5% 60-65% 25-35% 5-10% 60-65% 20-30% 10-15% 60-65% 15-25% 15-20% 60-65% 10-20% 20-25%60-65%  5-15% 25-30% 60-65%  1-10% 30-34% 65-70% 25-34% 1-5% 65-70%20-30%  5-10% 65-70% 15-25% 10-15% 65-70% 10-20% 15-20% 65-70%  5-15%20-25% 70-75% 20-29% 1-5% 70-75% 15-25%  5-10% 70-75% 10-20% 10-15%70-75%  5-15% 15-20% 75-80% 15-24% 1-5% 75-80% 10-20%  5-10% 75-80% 5-15% 10-15%

The concentration of sugar in the carbohydrate feedstock is typically inthe range of from or any number in between 2 wt % to 80 wt % or from orany number in between 5 wt % to 80 wt %. In various embodiments, theconcentration of sugar is in the range of from or any number in between20 wt % to 80 wt %. In some embodiments, the concentration of sugar inthe carbohydrate feedstock is in the range of from or any number inbetween 5 wt % to 20 wt %. In other embodiments, the concentration ofsugar in the carbohydrate feedstock is in the range of from or anynumber in between 5 wt % to 40 wt %. In some embodiments, theconcentration of sugar in the carbohydrate feedstock ranges from or anynumber in between 5-15 wt %, 10-20 wt %, 15-25 wt %, 20-30 wt %, 25-35wt %, 30-40 wt %, 35-45 wt %, 40-50 wt %, 45-55 wt %, 50-60 wt %, 55-65wt %, 60-70 wt %, 65-75 wt % or 70-80 wt %, or within a range defined byany two of the aforementioned weight percentages.

Catalysts that are suitable for use in the dehydration process includehomogeneous catalysts, including, for example, homogeneous acidcatalysts, and the like, as well as heterogeneous catalysts. Suitablehomogeneous acid catalysts include, for example, an inorganic acid, suchas, for example, a mineral acid (e.g., H₂SO₄, HNO₃, HCl, HBr, or HI, andthe like, as well as any combination of two or more thereof), a Brønstedacid (e.g., HCl, HI, H₂SO₄, HNO₃, H₃PO₄, oxalic acid, methanesulfonicacid, or trifluoromethanesulfonic acid, and the like, as well as anycombination of any two or more thereof), a Lewis acid (e.g., aborontrihalide, an organoborane, an aluminum trihalide, a phosphoruspentafluoride, an antimony pentafluoride, a rare earth metal triflate, ametal halide (e.g., ZnCl₂ and ZnBr₂), a metal trifluoroacetate or ametal cation ether complex, and the like, as well as any combination oftwo or more thereof), an organic acid (e.g., triflic acid,methansulfonic acid, benzenesulfonic acid, p-toluene sulfonic acid,oxalic acid, or levulinic acid, and the like, as well as any combinationof two or more thereof), and any combination thereof.

Quantities of homogeneous catalyst employed are typically in the rangeof from or any number in between 0.1 to 25 mol %, and more typically inthe range of from or any number in between 0.5 to 5 mol % (wherein, mol% is calculated on the basis of moles of sugar, e.g., hexose).Heterogeneous catalysts that are suitable for use in the practice of thepresent disclosure include an acid-functionalized resin, an acidifiedcarbon, a zeolite, a micro- and/or meso-porous metal oxide, a sulfonatedmetal oxide, a phosphonated metal oxide, a clay, or a polyoxometallate,and combinations thereof. Preferred heterogeneous catalysts includeacid-functionalized resins. The heterogeneous catalyst loading istypically in the range of or any number in between 1 g/L to 20 g/L in aslurry reactor, (such as e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19 or 20 g/L) and in the range of from or anynumber in between 200 g/L to 1500 g/L (such as e.g., 200, 300, 400, 500,600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500 g/L) in afixed bed reactor. The skilled artisan will recognize that theheterogeneous catalyst loading will vary depending on the specific typeof reactor used, but can readily determine the loading based on theseguidelines.

In a further specific embodiment, the present disclosure provides aprocess for producing a furanic oxidation substrate, the processcomprising:

(a^(o)) contacting a carbohydrate feedstock comprising a sugar and adehydration solvent with an acid catalyst under conditions sufficient toform a (dehydration) reaction mixture for dehydrating the sugar toproduce a furanic oxidation substrate, wherein the acid catalyst is anacid selected from the group consisting of HBr, H₂SO₄, HNO₃, HCl, HI,H₃PO₄, triflic acid, methansulfonic acid, benzenesulfonic acid, andp-toluene sulfonic acid,

wherein when the acid catalyst is not HBr, the reaction mixture furthercomprises a bromide salt, and

wherein the dehydration solvent comprises NMP. Typically, the acidcatalyst is a homogeneous acid catalyst. Suitable organic acids includethose mentioned hereinabove. Suitable bromide salts include LiBr, NaBr,KBr, MgBr₂, CaBr₂, ZnBr₂, or ammonium bromide salts having the chemicalstructure of R₄N⁺Br⁻, where R is a C₁-C₆ alkyl group. Exemplary ammoniumbromide salts include, but are not limited to, tetramethylammoniumbromide, tetraethylamminium bromide, tetrapropylammonium bromide, ortetrabutylammonium bromide, and the like. The quantity of bromide saltemployed is typically in molar excess of the acid present in thereaction mixture.

Quantities of acid catalyst employed are typically in the range of fromor any number in between 0.1 to 25 mol %, and more typically in therange of from or any number in between 0.5 to 5 mol % (wherein, mol % iscalculated on the basis of moles of sugar, e.g., hexose). In someembodiments, the amount of acid catalyst in the reaction mixture fordehydrating the sugar results in the reaction mixture having an acidicpH. In some embodiments, the amount of acid catalyst in the reactionmixture for dehydrating the sugar results in the reaction mixture havinga pH of less than 6. In some embodiments, the amount of acid catalyst inthe reaction mixture for dehydrating the sugar results in the reactionmixture having a pH of less than 5. In some embodiments, the amount ofacid catalyst in the reaction mixture for dehydrating the sugar resultsin the reaction mixture having a pH of less than 4. In some embodiments,the amount of acid catalyst in the reaction mixture for dehydrating thesugar results in the reaction mixture having a pH of less than 3. Insome embodiments, the amount of acid catalyst in the reaction mixturefor dehydrating the sugar results in the reaction mixture having a pH ofless than 2. In some embodiments, the amount of acid catalyst in thereaction mixture for dehydrating the sugar results in the reactionmixture having a pH of less than 1.

The dehydration reaction mixtures described hereinabove are typicallymaintained at a temperature in the range of from or any number inbetween 50° C. to 250° C., (such as e.g., 50, 60, 70, 80, 90, 100, 110,120, 130, 140, 150, 160, 180, 190, 200, 210, 220, 230, 240, or 250° C.or within a range defined by any two of the aforementioned temperatures)and a pressure in the range of from or any number in between 1 atm to 15atm, or from or any number in between 2 atm to 15 atm (such as e.g., 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 14, or 15 atm). More typically,the dehydration reaction mixture is maintained at a temperature in therange of from or any number in between 80° C. to 180° C. (such as e.g.,80, 90, 100, 110, 120, 130, 140, 150, 160, 180° C. or within a rangedefined by any two of the aforementioned temperatures). In someembodiments, the dehydration mixture is maintained at a temperature inthe range of from or any number in between 80° C. and 160° C., or 80° C.and 150° C., or 80° C. and 140° C., or 80 and 130° C., or 80° C. and120° C., or 80° C. and 110° C., or 80° C. and 100° C. In someembodiments, the dehydration mixture is maintained at a temperature thatis less than 110° C., or less than 100° C. Applicants have discoveredthat the dehydration mixture of the present disclosure can providesurprisingly high yields of furanic oxidation substrate at relativelylow temperatures of less than 110° C., such as less than 100° C.

To minimize production of undesired products, and maximize yield of thefuranic oxidation substrate, it may be desirable to carry out thedehydration reaction to a partial conversion endpoint, as described inWO 2015/113060 (which is incorporated herein by reference), by quenchingthe reaction, and separating and recycling unconverted sugar, by, forexample, filtration. When the furanic oxidation substrate is generatedby the dehydration reaction, it is present in a dehydration productsolution. As used herein, the term “dehydration product solution” refersto a solution comprising the furanic oxidation substrate and thedehydration solvent. The dehydration product solution can be a mixturethat includes dissolved furanic oxidation substrate and one or morecomponents that are not dissolved, wherein the one or more componentsthat are not dissolved are selected from humin and unreacted sugar. Thefuranic oxidation substrate may be optionally separated from one or morecomponents selected from the group consisting of a humin and anunreacted sugar and/or isolated from the dehydration product solution,and optionally further purified. In one such embodiment, the dehydrationproduct solution is subjected to a membrane to effect the separation ofthe furanic oxidation substrate from one or more components selectedfrom the group consisting of a humin and an unreacted sugar. Membranessuitable for use for such separation include nanofiltration membranes,ultrafiltration membranes, and combination thereof.

The dehydration product solution may be used as a feedstock forproducing an FDCA pathway product or derivative thereof, or anothersubsequent process that utilizes the furanic oxidation substrate.Typically, the furanic oxidation substrate is HMF.

The dehydration of the carbohydrate feedstock to produce the furanicoxidation substrate can produce the furanic oxidation substrate in yieldthat is typically at least 60% (on a molar basis). In some embodiments,the yield is at least 70%, and in other embodiments, it is at least 80%,at least 90%, at least 95%, at least 98% or at least 99%. In someembodiments, the yield ranges from between 60-65%, 62-67%, 65-70%,67-72%, 70-75%, 72-77%, 75-80%, 77-82%, 80-85%, 82-87%, 85-90%, 87-92%,90-95%, 92-97%, 95-98%, or 97-99%, or is within a range defined by anyof two of the aforementioned percentages.

In a specific embodiment, prior to step (a) of the FDCA pathwayproduct-generating oxidation processes of the present disclosure, step(a^(o)) is carried out to produce a furanic oxidation substrate in adehydration product solution. The dehydration product solution can beused either directly or indirectly (i.e., with one or more interveningpre-treatment step(s)), as the oxidation feedstock for step (a). Thepre-treatment step(s) may include a separation step (e.g., filtration ormembrane separation step (such as, for example ultrafiltration ornanofiltration), chromatography, ion exchange, and the like), adistillation step (to remove all or a portion of a component solvent),or other similar step/process suitable for amending the composition ofthe dehydration product solution to conform to a desired composition orform of the oxidation feedstock to be used in step (a). In thisembodiment, the dehydration solvent typically comprises at least onesolvent species in common with the oxidation solvent. One or moreadditional solvent species may be added to the dehydration productsolution during a pre-treatment step to formulate the dehydrationproduct solution into a desired oxidation feedstock composition for usein step (a). To illustrate, the dehydration solvent may be awater-miscible aprotic organic solvent. After conducting step (a^(o)),but before performing step (a), water can be added to the dehydrationproduct solution in a pre-treatment step, and the resulting oxidationfeedstock, comprising the furanic oxidation substrate and oxidationsolvent (i.e., in this example, a multi-component solvent made up of thewater-miscible aprotic organic solvent and water) can be used in step(a). Alternatively, the dehydration product solution can be useddirectly (i.e., as is) as the oxidation feedstock for step (a). In thisembodiment, the dehydration production solution comprises a dehydrationsolvent that is typically a multi-component solvent comprising water andan aprotic organic solvent (i.e., a multi-component solvent that issuitable for use as the oxidation solvent).

The foregoing and other aspects of the disclosure may be betterunderstood in connection with the following non-limiting examples.

EXAMPLES Example 1 FDCA Solubility Characterization

Solvents were screened for the ability to dissolve FDCA. 10 ml of acandidate solvent was heated to a certain temperature and FDCA (ProductNo. F0710, TCI America) was added by small portions to the heatedcandidate solvent until the FDCA amount exceeded the solubility limit.After that, small volumes of solvent were added until the excess solidswere completely dissolved. The experiment was repeated two times at eachtemperature and the average was taken as FDCA solubility. Five solventswere tested: (1) deionized water; (2) diglyme; (3) dioxane; (4) a 1:1 byvolume mixture of diglyme with deionized water; and (5) a 4:1 by volumemixture of dioxane with deionized water. The results are depicted inFIG. 3 as a plot of FDCA Solubility (Weight %) as a function oftemperature (° C.). The results show that FDCA appears to haverelatively low solubilities in each of water, diglyme, and dioxane inthe temperature range of 25° C. to 100° C. However, when each of theorganic solvents was combined with water, the resulting co-solventappeared to provide a synergistic enhancement in FDCA solubilizingcapability. For example, at 100° C., although FDCA solubility in waterand diglyme individually was less than 1% (by weight) and less than 2%(by weight), respectively, FDCA solubility reached 9% (by weight) whenthe two solvents were combined in a co-solvent system of 1:1 ratio ofdeionized water:diglyme, by volume. Similarly, at 100° C., although FDCAsolubility in water and dioxane individually was less than 1% (byweight) and less than 2% (by weight), respectively, the FDCA solubilitytrend line for the co-solvent system of 1:4 ratio of deionizedwater:dioxane, by volume, indicates 9% (by weight) FDCA solubility.

Example 2 Preparation of Heterogeneous Oxidation Catalyst (3 wt %Pt/silica)

A metal precursor solution was first prepared by mixing 0.152 ml of asolution of Pt(NH₃)₄(OH)₂ (containing 101.8 mg Pt/ml) with 0.047 ml ofde-ionized water. This solution was used to impregnate 0.5 g of silica(Cariact Q-50, BET specific surface area 80 m²/g, mean pore diameter 50nm, particle size 75-150 μm, Fuji Silysia Corporation). Afterimpregnation, the material was dried at 120° C. for two hours, thenreduced under a flow of 6% H₂ in argon at 300° C. for two hours. Aftercooling, the material was passivated under a flow of 0.5% O₂ in nitrogenfor 15 minutes. The resultant material, containing a 3 wt % Pt loading,was used for catalytic activity testing, as described in Example 11,without any further pretreatment.

Examples 3 and 4 Preparation of Heterogeneous Oxidation Catalyst (2.5 wt% Pt/Silica and 4 wt % Pt/Silica)

Heterogeneous oxidation catalysts were prepared as described in Example2 except that 0.204 ml of Pt(NH₃)₄(OH)₂ solution (containing 62.8 mgPt/ml) and 0.546 ml of deionized water, was used to prepareheterogeneous oxidation catalysts with platinum loadings of 2.5 wt %(Example 3) and 0.205 ml of Pt(NH₃)₄(OH)₂ solution (containing 101.8 mgPt/ml) and 0.42 ml de-ionized water were used to prepare catalyst with aplatinum loading of 4 wt % (Example 4). The resultant materials wereused for catalytic activity testing as described in Example 11.

Example 5 Preparation of Heterogeneous Oxidation Catalyst (3 wt %Pt/ZrO₂)

A metal precursor solution was first prepared by mixing 0.152 ml of asolution of Pt(NH₃)₄(OH)₂ (containing 101.8 mg Pt/ml) with 0.048 ml ofdeionized water. This solution was used to impregnate 0.5 g ZrO₂(SZ31163, BET specific surface area 55 m²/g, bimodal pore sizedistributions with mean pore diameters of 16 and 60 nm, particle size<150 μm, Saint Gobain). After impregnation, the material was dried at120° C. for 2 hours and then reduced under a flow of 6% H₂ in argon at300° C. for 2 hours. After cooling, the material was passivated under aflow of 0.5% O₂ in nitrogen for 15 minutes. The resultant material,containing a 3 wt % Pt loading, was used for catalytic activity testing,as described in Example 11, without any further pretreatment.

Example 6 Preparation of Heterogeneous Oxidation Catalyst (4 wt %Pt/ZrO₂)

The heterogeneous oxidation catalyst was prepared as described inExample 5 except 0.205 ml of the same Pt(NH₃)₄(OH)₂ solution was used toprepare a material with a platinum loading of 4 wt %. The resultantmaterial was used for catalytic testing as described in Example 11.

Example 7 Preparation of Heterogeneous Oxidation Catalyst (3 wt %Pt/Al₂O₃)

A metal precursor solution was first prepared by mixing 0.152 ml of asolution of Pt(NH₃)₄(OH)₂ (containing 101.8 mg Pt/ml) with 0.298 ml ofdeionized water. This solution was used to impregnate 0.5 g Al₂O₃ (SA31132, BET specific surface area 55 m²/g, bimodal with mean porediameters of 25 and 550 nm, particle size <150 μm, Saint Gobain). Afterimpregnation, the material was dried at 120° C. for 2 hours. Finally,the material was reduced under flow of 6% H₂ in argon at 300° C. for 2hours. After cooling, the material was passivated under a flow of 0.5%O₂ in nitrogen for 15 minutes. The resultant material, containing a 3 wt% Pt loading, was used for catalytic activity testing, as described inExample 11, without any further pretreatment.

Example 8 Preparation of Heterogeneous Oxidation Catalyst (4 wt %Pt/Al₂O₃)

The heterogeneous oxidation catalyst in this example was prepared in themanner described in Example 7, except that 0.205 ml of the samePt(NH₃)₄(OH)₂ solution and 0.245 ml of de-ionized water were used toprepare a metal precursor solution that was used to prepare materialwith a platinum loading of 4 wt %. The resultant material was used forcatalytic activity testing as described in Example 11.

Examples 9 and 10 Preparation of Heterogeneous Oxidation Catalysts

(2 wt % Pt, 1 wt % Au/silica; 1 wt % Pt, 2 wt % Au/silica) A metalprecursor solution was first prepared by mixing 0.018 ml of a solutionof PtONO₃ (containing 100 mg Pt/ml) with 0.009 ml of a solution of(NH₄)₂AuO₂ (containing 100 mg Au/ml) and 0.09 ml of deionized water(Example 9), and correspondingly mixing 0.009 ml of the PtONO₃ solution(containing 100 mg Pt/ml) with 0.018 ml of (NH₄)₂AuO₂ solution(containing 100 mg Au/ml) and 0.09 ml deionized water (Example 10). Eachsolution was used to impregnate 0.1 g of silica (Cariact Q-50, particlesize 75-150 μm, specific surface area 80 m²/g, mean pore diameter 50 nm,Fuji Silisia Corporation). After impregnation, material was reducedunder flow of 6% H₂ in argon at 350° C. for 3 hours. After cooling, thematerial was passivated under a flow of 0.5% O₂ in nitrogen for 15minutes. The resultant materials, containing a 2 wt % Pt loading and a 1wt % Au loading (Example 9) and containing a 1 wt % Pt, 2 wt % Auloading (Example 10) were used for catalytic activity testing, asdescribed in Example 11, without any further pretreatment.

Example 11 Catalyst Performance Assay and Production of FDCA PathwayProducts

Catalyst testing was conducted within 1 ml glass vials housed in a96-well insert situated in a high pressure high throughput reactor. SeeDiamond, G. M., Murphy, V., Boussie, T. R., in Modern Applications ofHigh Throughput R&D in Heterogeneous Catalysis, (eds, Hagemeyer, A. andVolpe, A. Jr. Bentham Science Publishers 2014, Chapter 8, 299-309); seealso U.S. Pat. No. 8,669,397, both of which are incorporated herein byreference. 20 mg of each catalyst was placed into the reactor along with0.8 ml of a 0.5 M HMF solution prepared in a 4:1 (v/v) dioxane:H₂Omixture (this corresponds to 6 wt % of HMF). The 1 ml reaction vialswithin the insert were each covered with a Teflon sheet, a silicon matand a steel gas diffusion plate each containing pin-holes to enable gasentry. The insert was placed within a pressure vessel which was leaktested under nitrogen pressure. The atmosphere within the reactor wasthen replaced by oxygen and the reactor was heated to 90° C. and shakenat 500 rpm for 20 hours, and at 200 psig oxygen pressure. After thereaction was completed, the shaking was stopped and the reactor wascooled down to room temperature. Samples were prepared for HPLC analysisby sampling from each reactor and diluting the sample by a factor of 200with a 4:1 dioxane:H₂O mixture. Reaction products werehydroxymethylfurancarboxylic acid (HMFCA), formylfurancarboxylic acid(FFCA), diformylfuran (DFF) and FDCA. The results are shown in Table 1.

TABLE 1 Catalyst Composition and Performance. BET Spe- cific Mean Sur-Pore Pt, Au, HMFCA DFF FFCA FDCA Ex- face Dia- Sup- wt wt Yield YieldYield Yield ample Area meter port % % % % % % 2 75 50 nm SiO₂ 3 0 0 0 191 3 75 50 nm SiO₂ 4 0 0 0 2 81 4 75 50 nm SiO₂ 2.5 0 0 0 4 85 5 55Bimodal ZrO₂ 3 0 0 0 31 52 16 nm & 60 nm 6 55 Bimodal ZrO₂ 4 0 0 0 21 5616 nm & 60 nm 7 55 Bimodal Al₂O₃ 3 0 0 0 32 37 25 nm & 550 nm 8 55Bimodal Al₂O₃ 4 0 0 0 30 36 25 nm & 550 nm 9 75 50 nm SiO₂ 2 1 0 0 30 4310 75 50 nm SiO₂ 1 2 2 10 40 10

At the relatively low metal loadings reported above, the BET specificsurface areas of the solid support materials are believed to remainunchanged in the formulated heterogeneous oxidation catalyst.

Example 12 Preparation and Testing of Carbon-Supported Catalysts

An aqueous solution (0.10 ml) containing 10 mg/ml Au added in the formof Me₄NAuO₂ and 20 mg/ml Pt added in the form of PtO(NO₃) was added tocarbon black powder (100 mg) of Cabot Monarch 570. The mixture wasagitated to impregnate the carbon black support and was dried in a 70°C. oven overnight under a dry air purge. The sample was then reduced at350° C. under forming gas (5% H₂ and 95% N₂) atmosphere for 2 hours with5° C./min temperature ramp rate. The final catalyst was composed of ca.1.0 wt % Au and 2.0 wt % Pt. By using other carbon black and adjustingamount of Au and Pt in solution, different catalysts with various Au andPt loadings on a variety of commercial carbon black powders or particlesfrom extrudates were prepared in a similar manner. The compositions forthese catalysts are listed in Table 2, hereinbelow.

These catalysts were tested for hydroxymethylfurfural (HMF) oxidationusing the following testing protocol. Catalyst (10 mg) was weighed intoa glass vial insert followed by addition of an aqueous HMF solution (250μl of 0.50 M or 6.0 wt % in 1,4-dioxane:water (4:1 v/v)). The glass vialinsert was loaded into a reactor and the reactor was closed. Theatmosphere in the reactor was replaced with oxygen and pressurized to200 psig at room temperature. The reactor was heated to 110° C. andmaintained at the respective temperature for 4 hours, or 90° C. andmaintained at the respective temperature for 20 hours, while the vialwas shaken. After that, shaking was stopped and reactor was cooled to40° C. The pressure in the reactor was then slowly released. The glassvial insert was removed from the reactor and centrifuged. The solutionwas diluted with 1,4-dioxane:water (4:1 v/v) and analyzed by HPLC with aUV detector to determine the yield of 2,5-furandicarboxylic acid (FDCA).The results are presented in Table 2.

TABLE 2 Catalyst Composition and Performance. BET Mean Sur- Pore FDCAface Diam- Yield Area eter Screening Metal (mol Carbon Support m²/g (nm)Condition Loading %) Cabot Monarch 120 23 28  90° C./20 h 3.0 wt % Pt 82Cabot Monarch 280 30 18  90° C./20 h 3.0 wt % Pt 88 Cabot Monarch 280 3018  90° C./20 h 1.0 wt % Au 60 2.0 wt % Pt Cabot Monarch 570 102 14  90°C./20 h 3.0 wt % Pt 84 Cabot Monarch 570 102 14  90° C./20 h 1.0 wt % Au68 2.0 wt % Pt Cabot Monarch 700 181 12  90° C./20 h 3.0 wt % Pt 81Cabot Monarch 700 181 12  90° C./20 h 1.0 wt % Au 73 2.0 wt % Pt SidRichardson SC159 231 13  90° C./20 h 3.0 wt % Pt 70 Timcal Ensaco 150G47 14  90° C./20 h 3.0 wt % Pt 82 Timcal Ensaco 250G 64 14  90° C./20 h3.0 wt % Pt 79 Cabot Monarch 120 23 28 110° C./4 h  3.0 wt % Pt 65 CabotMonarch 280 30 18 110° C./4 h  3.0 wt % Pt 73 Cabot Monarch 570 102 14110° C./4 h  3.0 wt % Pt 62 Cabot Monarch 700 181 12 110° C./4 h  3.0 wt% Pt 67 Timcal Ensaco 150G 47 14 110° C./4 h  3.0 wt % Pt 71

Example 13 Crystallization of FDCA from a Multi-Component SolventComprising Water and an Aprotic Organic Solvent

0.5 g FDCA was weighed into 2 vials with magnetic stirrers. In Vial 1, 3ml H₂O and 2 ml glyme were added. In Vial 2, 2 ml H₂O and 3 ml glyme wasadded. Insoluble milky white suspensions formed at room temperature. Thevials were heated with stirring to 140° C. in an oil bath. Thesuspension in Vial 1 turned into a clear solution with full apparentFDCA solubility at ˜130° C. The suspension in Vial 2 turned into a clearsolution with full apparent FDCA solubility at ˜110° C. As thetemperature of the clear solutions were slowly reduced to roomtemperature, FDCA crystallized to produce purified FDCA.

Description of Analytical Method

The analytical instrumentation used in the following examples was aThermo Scientific Dionex Ultimate System fitted with a Thermo ScientificHypercarb 3 μm 3×50 mm analytical column and a 3000 RS VariableWavelength UV/Vis Detector.

Example 14 Preparation of 40 g Heterogeneous Oxidation Catalyst (3.0 wt.% Pt/Carbon)

A metal precursor solution was first prepared by mixing 5.64 ml of asolution of platinum nitrate (containing 219 mg Pt/ml from HeraeusGroup) and 94.4 ml of deionized water. This solution was used toimpregnate 40.0 g of carbon powder (Continental N234 carbon blackpowder, BET surface area 117 m²/g, average pore diameter 14 nm). Afterimpregnation, the material was dried at 100° C. for 3 hours and thenreduced under a flow of 5% H₂ in nitrogen at 350° C. for 3 hours with 5°C./min temperature ramp rate. After cooling, the material was passivatedunder a flow of 0.5% O₂ in nitrogen for 15 minutes. The resultantmaterial, containing a 3.0 wt. % Pt loading, was used for catalyticactivity testing as described in Example 15, without any furtherpretreatment.

Example 15 Testing of Carbon-Supported Catalyst in Parr Pressure Reactor

Catalyst testing was conducted in a 300 ml Parr stainless steelautoclave pressure reactor. Catalyst was weighed (e.g., 8.00 g of 3.0wt. % Pt/Continental N₂₃₄ carbon black powder) and placed into reactor,along with a substrate HMF (5-(hydroxymethyl)furfural) solution (100 g6.0 wt. % prepared in either a 65 wt. % DME/35 wt. % H₂O solvent mixtureor a 60 wt. % 1,4-Dioxane/40 wt. % H₂O solvent mixture). The reactor wasassembled and a magnetic drive coupled stirrer was attached.

The reactor was pressurized with process gas (O₂) to desired pressurewith stirring (1000 rpm) at ambient temperature, followed by heating totarget temperature and holding at that temperature for the plannedreaction time. After the ascribed reaction time, the reactor was cooledwith stirring lowered to ca. 200 rpm, and vented slowly at 30° C.

Dimethyl sulfoxide (DMSO) was added to the reactor for the first stepdilution. After stirring for ca. 30 min, the product solution wascentrifuged and further diluted with de-ionized water for HPLC analysis.

The reaction products were 5-Hydroxymethyl-furan-2-carboxylic acid(HMFCA), 2,5-Furandicarboxaldehyde (DFF), 5-Formylfuran-3-carboxylicacid (FFCA), and 2,5-Furandicarboxylic Acid (FDCA). Each of aboveproducts as well as any remaining HMF was quantified through acalibration curve for each analyte by plotting the relativeconcentration vs. the relative detector response of calibration standardsamples and fit to a parabolic expression. Results are summarized inTable 3.

TABLE 3 Catalyst Performance in Parr Pressure Reactor. O₂ Reaction FFCAFDCA Mass Run Catalyst Temp. Pressure Time Yield Yield Balance (mol No.(g) (° C.) (psig) (min) Solvent (mol %) (mol %) %) 1 8.00 120 200 90 65wt. % DME/ 1.1 90.0 91.1 35 wt. % H₂O 3 8.00 110 250 90 65 wt. % DME/4.9 91.3 96.2 35 wt. % H₂O 4 8.00 110 250 120 60 wt. % 2.7 92.4 95.1Dioxane/ 40 wt. % H₂OMass balance represent the sum of the mol % yields of HMF, HMFCA, DFF,FFCA and FDCA.

Example 16 Preparation and Testing of a Variety of Carbon-SupportedCatalysts

An aqueous solution (0.60 ml) containing 10 mg/ml Pt in the form ofplatinum nitrate was added to carbon black powder (200 mg), and theresultant material was agitated to impregnate the supports. The sampleswere then dried in an oven at 70° C. overnight, and reduced at 350° C.under a forming gas (5% H₂ and 95% N₂) atmosphere for 3 hours with 5°C./min temperature ramp rate to produce catalyst with a composition of3.0 wt. % Pt. By using other carbon black supports, Pt precursors, andadjusting amount of Pt in solution, different catalysts with various Ptloadings on a variety of commercial carbon black powders, particles fromextrudates, or extrudates can be prepared in a similar manner.

These catalysts were tested for 5-(Hydroxymethyl)furfural (HMF)oxidation using the following testing protocol. Catalyst (10 mg) wasweighed into a 1 ml glass vial insert followed by addition of an HMFsolution (250 al of 6.0 wt. % or 0.50 M in 23 wt. % Diglyme/77 wt. %H₂O). The glass vial insert was loaded into a reactor and the reactorwas closed. The atmosphere in the reactor was replaced with oxygen andpressurized to 200 psig at ambient temperature. The reactor was heatedto 110° C. and maintained at the respective temperature for 3 hourswhile the vial was shaken. After that, shaking was stopped and reactorwas cooled to 40° C. Pressure in the reactor was then slowly released.The glass vial insert was removed from the reactor and centrifuged. Thesolution was diluted with dimethyl sulfoxide (DMSO) followed by1,4-dioxane:water (2:1 v/v) and analyzed by HPLC with a UV detector todetermine the yield of 2,5-furandicarboxylic acid (FDCA). Results arepresented in Table 4.

TABLE 4 Catalyst Performance. BET Surface FDCA Carbon Support Area(m²/g) Yield (mol %) Orion Arosperse 15 9 66 Asbury A99 19 44 Orion LampBlack 101 20 82 Cabot Monarch 120 23 80 Cabot Monarch 280 30 82 Asbury5375R 30 77 Asbury 5365R 34 81 Asbury 5345 37 80 Continental N550 38 80Continental N120 39 80 Arosperse 5-183A 42 79 Timcal Ensaco 150G 47 77Timcal Ensaco 250G 56 80 Timcal Ensaco 260G 63 79 Asbury 5348R 65 80Asbury 5358R 67 81 Orion N330 76 78 Continental N330-C 77 80 CabotMonarch 570 102 77 Orion HiBlack 40B2 109 58 Continental N234 117 81Orion Arosperse 138 120 74 Sid Richardson Ground N115 128 70 SidRichardson SC419 136 76 Sid Richardson Ground SR155 146 63 Orion HP-160158 59 Aditya Birla CDX-KU 167 63 Aditya Birla CSCUB 169 64 CabotMonarch 700 181 65 Orion Hi-Black 50 LB 183 69 Aditya Birla R2000B 18767 Orion Hi-Black 50L 193 73 Asbury 5302 211 68 Asbury 5303 219 65 CabotVulcan XC72 231 62 Sid Richardson SC159 231 51 Orion Hi-Black 600 L 23570 Aditya Birla R250OUB 247 46 Orion Printex L 6 250 54 Asbury 5379 27152 Asbury 5368 303 68 Aditya Birla R3500B 320 60 Orion Color Black FW 2350 61 Aditya Birla R5000U2 583 61 Cabot Norit Darco 12x20L1 592 12Orion Color Black FW 255 650 58 Timcal Ensaco 350G 770 31

Example 17 Testing of Carbon-Supported Powder Catalysts in a Variety ofSolvent Compositions

A selection of above catalysts were tested for 5-(Hydroxymethyl)furfural(HMF) oxidation with very similar testing protocol by using 10 mg 3.0wt. % Pt on carbon black powder (prepared from platinum nitrate) in anHMF solution (250 al of 6.0 wt. % or 0.50 M in a variety of solventmixtures of water with DME, 1,4-dioxane and diglyme). The glass vialinsert was loaded into a reactor and the reactor was closed. Theatmosphere in the reactor was replaced with oxygen and pressurized to200 psig at ambient temperature. The reactor was heated to 110° C. andmaintained at the respective temperature for 3 hours while the vial wasshaken. After that, shaking was stopped and reactor was cooled to 40° C.The pressure in the reactor was then slowly released. The glass vialinsert was removed from the reactor and centrifuged. The solution wasdiluted with dimethyl sulfoxide (DMSO) followed by 1,4-dioxane:water(2:1 v/v) and analyzed by HPLC with a UV detector to determine the yieldof 2,5-furandicarboxylic acid (FDCA). The results are presented in Table5.

TABLE 5 Powder Catalyst Performance in Various Solvent Compositions BETSur- FDCA face Yield Area (mol Carbon Support (m²/g) Solvent %) Asbury5358R 67 50 wt. % DME/50 wt. % H₂O 81 Asbury 5375R 30 50 wt. % DME/50wt. % H₂O 72 Cabot Monarch 280 30 50 wt. % DME/50 wt. % H₂O 79Continental N234 117 50 wt. % DME/50 wt. % H₂O 81 Continental N330 77 50wt. % DME/50 wt. % H₂O 81 Orion Arosperse 42 50 wt. % DME/50 wt. % H₂O79 5-183A Orion Lamp Black 101 20 50 wt. % DME/50 wt. % H₂O 81 TimcalEnsaco 250G 56 50 wt. % DME/50 wt. % H₂O 80 Asbury 5358R 67 90 wt. %DME/10 wt. % H₂O 51 Asbury 5375R 30 90 wt. % DME/10 wt. % H₂O 31 CabotMonarch 280 30 90 wt. % DME/10 wt. % H₂O 50 Continental N234 117 90 wt.% DME/10 wt. % H₂O 50 Continental N330 77 90 wt. % DME/10 wt. % H₂O 54Orion Arosperse 42 90 wt. % DME/10 wt. % H₂O 50 5-183A Orion Lamp Black101 20 90 wt. % DME/10 wt. % H₂O 51 Timcal Ensaco 250G 56 90 wt. %DME/10 wt. % H₂O 50 Asbury 5358R 67 50 wt. % Dioxane/50 wt. % H₂O 73Asbury 5375R 30 50 wt. % Dioxane/50 wt. % H₂O 60 Cabot Monarch 280 30 50wt. % Dioxane/50 wt. % H₂O 73 Continental N234 117 50 wt. % Dioxane/50wt. % H₂O 71 Continental N330 77 50 wt. % Dioxane/50 wt. % H₂O 74 OrionArosperse 42 50 wt. % Dioxane/50 wt. % H₂O 72 5-183A Orion Lamp Black101 20 50 wt. % Dioxane/50 wt. % H₂O 74 Timcal Ensaco 250G 56 50 wt. %Dioxane/50 wt. % H₂O 76 Asbury 5358R 67 82 wt. % Dioxane/18 wt. % H₂O 53Asbury 5375R 30 82 wt. % Dioxane/18 wt. % H₂O 30 Cabot Monarch 280 30 82wt. % Dioxane/18 wt. % H₂O 54 Continental N234 117 82 wt. % Dioxane/18wt. % H₂O 48 Continental N330 77 82 wt. % Dioxane/18 wt. % H₂O 52 OrionArosperse 42 82 wt. % Dioxane/18 wt. % H₂O 48 5-183A Orion Lamp Black101 20 82 wt. % Dioxane/18 wt. % H₂O 53 Timcal Ensaco 250G 56 82 wt. %Dioxane/18 wt. % H₂O 50 Asbury 5358R 67 23 wt. % Diglyme/77 wt. % H₂O 75Asbury 5375R 30 23 wt. % Diglyme/77 wt. % H₂O 73 Cabot Monarch 280 30 23wt. % Diglyme/77 wt. % H₂O 77 Continental N234 117 23 wt. % Diglyme/77wt. % H₂O 75 Continental N330 77 23 wt. % Diglyme/77 wt. % H₂O 77 OrionArosperse 42 23 wt. % Diglyme/77 wt. % H₂O 76 5-183A Orion Lamp Black101 20 23 wt. % Diglyme/77 wt. % H₂O 79 Timcal Ensaco 250G 56 23 wt. %Diglyme/77 wt. % H₂O 76 Asbury 5358R 67 50 wt. % Diglyme/50 wt. % H₂O 75Asbury 5375R 30 50 wt. % Diglyme/50 wt. % H₂O 68 Cabot Monarch 280 30 50wt. % Diglyme/50 wt. % H₂O 73 Continental N234 117 50 wt. % Diglyme/50wt. % H₂O 74 Continental N330 77 50 wt. % Diglyme/50 wt. % H₂O 74 OrionArosperse 42 50 wt. % Diglyme/50 wt. % H₂O 73 5-183A Orion Lamp Black101 20 50 wt. % Diglyme/50 wt. % H₂O 74 Timcal Ensaco 250G 56 50 wt. %Diglyme/50 wt. % H₂O 73

Example 18 Preparation and Testing of Carbon-Based Extrudate Catalystsin a Variety of Solvent Mixtures

An aqueous solution (0.25 ml) containing 60 mg/ml Pt in the form ofplatinum nitrate was added to carbon extrudates (average 3 mm length and0.75 mm diameter, 500 mg, prepared as described in WO 2015/168327, whichis incorporated herein by reference), and the resultant material wasagitated to impregnate the supports. The samples were then dried in anoven at 100° C. for 3 hours, and reduced at 350° C. under a forming gas(5% H₂ and 95% N₂) atmosphere for 3 hours with 5° C./min temperatureramp rate to produce catalyst with a composition of 3.0 wt. % Pt. Byusing other carbon-based extrudate supports, Pt precursors, andadjusting the amount of Pt in solution, different catalysts with variousPt loadings on a variety of carbon-based extrudate supports wereprepared in a similar manner.

Above catalysts were tested for 5-(Hydroxymethyl)furfural (HMF)oxidation with a very similar testing protocol by using 15 mg 3.0 wt. %Pt on extrudates of average 3 mm length and 0.75 mm diameter in an HMFsolution (250 μl of 6.0 wt. % or 0.50 M in a variety of solvent mixturesof water with DME, 1,4-dioxane, diglyme, triglyme, tetraglyme andhiglyme). The glass vial insert was loaded into a reactor and thereactor was closed. The atmosphere in the reactor was replaced withoxygen and pressurized to 200 psig at ambient temperature. The reactorwas heated to 120° C. and maintained at the respective temperature for 2hours while the vial was shaken. After that, shaking was stopped andreactor was cooled to 40° C. Pressure in the reactor was then slowlyreleased. The glass vial insert was removed from the reactor andcentrifuged. The solution was diluted with dimethyl sulfoxide (DMSO)followed by 1,4-dioxane:water (2:1 v/v) and analyzed by HPLC with a UVdetector to determine the yield of 2,5-furandicarboxylic acid (FDCA).The results are presented in Table 6.

TABLE 6 Extrudate Catalyst (average 3 mm length and 0.75 mm diameter)Performance in Various Solvent Mixtures. BET Sur- FDCA face Yield Area(mol Carbon Support (m²/g) Solvent %) Timcal Ensaco 250G 123 50 wt. %Dioxane/50 wt. % H₂O 65 Orion Arosperse 91 50 wt. % Dioxane/50 wt. % H₂O59 5-183A Continental N120 98 50 wt. % Dioxane/50 wt. % H₂O 52Continental N234 137 50 wt. % Dioxane/50 wt. % H₂O 39 Continental N330115 50 wt. % Dioxane/50 wt. % H₂O 59 Continental N550 88 50 wt. %Dioxane/50 wt. % H₂O 56 Timcal Ensaco 250G 123 50 wt. % Diglyme/50 wt. %H₂O 62 Orion Arosperse 91 50 wt. % Diglyme/50 wt. % H₂O 24 5-183AContinental N234 137 50 wt. % Diglyme/50 wt. % H₂O 24 Continental N330115 50 wt. % Diglyme/50 wt. % H₂O 43 Timcal Ensaco 250G 123 50 wt. %Triglyme/50 wt. % H₂O 38 Timcal Ensaco 250G 123 50 wt. % Tetraglyme/50wt. % H₂O 18 Timcal Ensaco 250G 123 50 wt. % Higlyme/50 wt. % H₂O 16

Example 19 Testing of Carbon-Supported Powder Catalysts in a Variety ofSolvent Mixtures

5, 10, 15, or 20 mg 3.0 wt. % Pt on Continental N234 carbon black powder(prepared from platinum nitrate) was tested for5-(Hydroxymethyl)furfural (HMF) oxidation using a very similar testingprotocol to Example 5 in an HMF solution (250 al of 6.0 wt. % or 0.50 Min a variety of solvent mixtures of water and 1,4-dioxane with differentratios). The glass vial insert was loaded into a reactor and the reactorwas closed. The atmosphere in the reactor was replaced with oxygen andpressurized to 200 psig at ambient temperature. The reactor was heatedto 110° C. and maintained at the respective temperature for 3 hourswhile the vial was shaken. After that, shaking was stopped and thereactor was cooled to 40° C. Pressure in the reactor was then slowlyreleased. The glass vial insert was removed from the reactor andcentrifuged. The solution was diluted with dimethyl sulfoxide (DMSO)followed by 1,4-dioxane:water (2:1 v/v) and analyzed by HPLC with a UVdetector to determine the yield of 2,5-furandicarboxylic acid (FDCA).Results are presented in Table 7.

TABLE 7 Powder Catalyst Performance in Various Dioxane/H₂O SolventMixtures. Catalyst FDCA (mg) Solvent Yield (%) 5 100 wt. % Dioxane 0 10100 wt. % Dioxane 3 15 100 wt. % Dioxane 7 20 100 wt. % Dioxane 11 5 90wt. % Dioxane/10 wt. % H₂O 14 10 90 wt. % Dioxane/10 wt. % H₂O 38 15 90wt. % Dioxane/10 wt. % H₂O 54 20 90 wt. % Dioxane/10 wt. % H₂O 64 5 80wt. % Dioxane/20 wt. % H₂O 24 10 80 wt. % Dioxane/20 wt. % H₂O 56 15 80wt. % Dioxane/20 wt. % H₂O 72 20 80 wt. % Dioxane/20 wt. % H₂O 81 5 70wt. % Dioxane/30 wt. % H₂O 34 10 70 wt. % Dioxane/30 wt. % H₂O 65 15 70wt. % Dioxane/30 wt. % H₂O 79 20 70 wt. % Dioxane/30 wt. % H₂O 84 5 60wt. % Dioxane/40 wt. % H₂O 37 10 60 wt. % Dioxane/40 wt. % H₂O 74 15 60wt. % Dioxane/40 wt. % H₂O 84 20 60 wt. % Dioxane/40 wt. % H₂O 88 5 50wt. % Dioxane/50 wt. % H₂O 43 10 50 wt. % Dioxane/50 wt. % H₂O 76 15 50wt. % Dioxane/50 wt. % H₂O 87 20 50 wt. % Dioxane/50 wt. % H₂O 89 5 40wt. % Dioxane/60 wt. % H₂O 46 10 40 wt. % Dioxane/60 wt. % H₂O 79 15 40wt. % Dioxane/60 wt. % H₂O 89 20 40 wt. % Dioxane/60 wt. % H₂O 91 5 20wt. % Dioxane/80 wt. % H₂O 55 10 20 wt. % Dioxane/80 wt. % H₂O 84 15 20wt. % Dioxane/80 wt. % H₂O 87 20 20 wt. % Dioxane/80 wt. % H₂O 86 5 100wt. % H₂O 68 10 100 wt. % H₂O 82 15 100 wt. % H₂O 82 20 100 wt. % H₂O 79

Example 20 Testing of Carbon-Supported Extrudate Catalysts

10 or 20 mg 2.0 wt. % Pt on Continental N234 carbon black extrudates(average length 3 mm and diameter 1.5 mm or 0.75 mm prepared fromPtO(NO₃)) was tested for 5-(Hydroxymethyl)furfural (HMF) oxidation usinga very similar testing protocol in an HMF solution (250 μl of 6.0 wt. %or 0.50 M in a 50 wt. % Dioxane/50 wt. % H₂O). The glass vial insert wasloaded into a reactor and the reactor was closed. The atmosphere in thereactor was replaced with oxygen and pressurized to 100, 200, or 400psig at ambient temperature. The reactor was heated to 120° C. andmaintained at the respective temperature for 2 hours while the vial wasshaken. After that, shaking was stopped and reactor was cooled to 40° C.Pressure in the reactor was then slowly released. The glass vial insertwas removed from the reactor and centrifuged. The solution was dilutedwith dimethyl sulfoxide (DMSO) followed by 1,4-dioxane:water (2:1 v/v)and analyzed by HPLC with a UV detector to determine the yield of2,5-furandicarboxylic acid (FDCA). The results are presented in Table 8.

TABLE 8 Extrudate Catalyst Performance in 50 wt. % Dioxane/50 wt. % H₂OSolvent Mixtures. Extrudate O₂ Pressure Catalyst FDCA Diameter (mm)(psig) (mg) Yield (mol %) 0.75 100 10 35 0.75 100 20 67 1.5 100 10 251.5 100 20 48 0.75 200 20 76 1.5 200 20 77 0.75 400 10 55 0.75 400 20 761.5 400 10 49 1.5 400 20 77

Example 21 Testing of Carbon-Supported Extrudate Catalysts

20 mg 2.0 wt. % or 3.0 wt. % Pt on carbon black extrudates (averagelength 3 mm and diameter 1.5 mm or 0.75 mm prepared from PtO(NO₃)) wastested for 5-(Hydroxymethyl)-furfural (HMF) oxidation using very similartesting protocol in an HMF solution (250 μl of 6.0 wt. % or 0.50 M in a50 wt. % Dioxane/50 wt. % H₂O). The glass vial insert was loaded into areactor and the reactor was closed. The atmosphere in the reactor wasreplaced with oxygen and pressurized to 200 psig at ambient temperature.The reactor was heated to 120° C. and maintained at the respectivetemperature for 2 hours while the vial was shaken. After that, shakingwas stopped and the reactor was cooled to 40° C. The pressure in thereactor was then slowly released. The glass vial insert was removed fromthe reactor and centrifuged. The solution was diluted with dimethylsulfoxide (DMSO) followed by 1,4-dioxane:water (2:1 v/v) and analyzed byHPLC with a UV detector to determine the yield of 2,5-furandicarboxylicacid (FDCA). The results are presented in Table 9.

TABLE 9 Extrudate Catalyst Performance in 50 wt. % Dioxane/50 wt. % H₂OSolvent Mixtures. Ex- trudate Ext- Mercury Carbon rudate Ex- Porosi- PtBlack Sur- trudate metry Load- FDCA Surface face Dia- Pore ing YieldArea Area meter Area (wt. (mol Support (m²/g) (m²/g) (mm) (m²/g) %) %)Orion Lamp Black 20 87 0.75 10 2.0 30 101 Asbury 5365R 34 92 0.75 18 2.012 Continental N550 38 88 0.75 21 2.0 67 Continental N120 39 98 0.75 192.0 68 Orion Arosperse 5- 42 91 0.75 20 2.0 69 183A Continental N330 77115 0.75 38 2.0 76 Continental N234 117 137 0.75 54 2.0 75 Cabot Monarch700 181 177 0.75 53 2.0 75 Norit ROX 0.8 1323 1323 0.75 24 2.0 42(Activated Carbon) Orion Lamp Black 20 87 0.75 10 3.0 37 101 Asbury5365R 34 92 0.75 18 3.0 45 Continental N550 38 88 0.75 21 3.0 61Continental N120 39 98 0.75 19 3.0 59 Orion Arosperse 5- 42 91 0.75 203.0 66 183A Continental N330 77 115 0.75 38 3.0 76 Continental N234 117137 0.75 54 3.0 79 Cabot Monarch 700 181 177 0.75 53 3.0 77 Norit ROX0.8 1323 1323 0.75 24 3.0 41 (Activated Carbon)

Example 22 Testing of Carbon-Supported Powder and Extrudate Catalysts inN-Methyl-2-Pyrrolidone/H₂O Solvent Compositions

10 or 20 mg 3.0 wt. % Pt on Continental N234 carbon black powder(prepared from platinum nitrate) or extrudates (average length 3 mm anddiameter 1.5 mm or 0.75 mm prepared from PtO(NO₃)) was tested for5-(Hydroxymethyl)furfural (HMF) oxidation using very similar testingprotocol in an HMF solution (250 μl of 6.0 wt. % or 0.50 M in a solventmixture of N-Methyl-2-Pyrrolidone (NMP) and H₂O). The glass vial insertwas loaded into a reactor and the reactor was closed. The atmosphere inthe reactor was replaced with oxygen and pressurized to 200 psig atambient temperature. The reactor was heated to 110° C. and maintained atthe respective temperature for 3 hours while the vial was shaken. Afterthat, shaking was stopped and the reactor was cooled to 40° C. Thepressure in the reactor was then slowly released. The glass vial insertwas removed from the reactor and centrifuged. The solution was dilutedwith dimethyl sulfoxide (DMSO) followed by 1,4-dioxane:water (2:1 v/v)and analyzed by HPLC with a UV detector to determine the yield of2,5-furandicarboxylic acid (FDCA). The results are presented in Table10.

TABLE 10 Powder and Extrudate Catalyst Performance in NMP/H₂O SolventMixtures. Catalyst FDCA Solvent Catalyst Amount Yield Composition Size(mg) (mol %) 100 wt. % NMP Powder 10 1 98 wt. % NMP/2 wt. % H₂O Powder10 1 95 wt. % NMP/5 wt. % H₂O Powder 10 1 90 wt. % NMP/10 wt. % H₂OPowder 10 4 85 wt. % NMP/15 wt. % H₂O Powder 10 7 80 wt. % NMP/20 wt. %H₂O Powder 10 15 70 wt. % NMP/30 wt. % H₂O Powder 10 23 60 wt. % NMP/40wt. % H₂O Powder 10 32 50 wt. % NMP/50 wt. % H₂O Powder 10 42 40 wt. %NMP/60 wt. % H₂O Powder 10 44 20 wt. % NMP/80 wt. % H₂O Powder 10 44 100wt. % H₂O Powder 10 80 100 wt. % NMP Powder 20 1 98 wt. % NMP/2 wt. %H₂O Powder 20 2 95 wt. % NMP/5 wt. % H₂O Powder 20 4 90 wt. % NMP/10 wt.% H₂O Powder 20 13 85 wt. % NMP/15 wt. % H₂O Powder 20 22 80 wt. %NMP/20 wt. % H₂O Powder 20 32 70 wt. % NMP/30 wt. % H₂O Powder 20 51 60wt. % NMP/40 wt. % H₂O Powder 20 57 50 wt. % NMP/50 wt. % H₂O Powder 2066 40 wt. % NMP/60 wt. % H₂O Powder 20 66 20 wt. % NMP/80 wt. % H₂OPowder 20 71 100 wt. % H₂O Powder 20 78 100 wt. % NMP 0.75 mm × 3 mm 2010 98 wt. % NMP/2 wt. % H₂O 0.75 mm × 3 mm 20 11 95 wt. % NMP/5 wt. %H₂O 0.75 mm × 3 mm 20 11 90 wt. % NMP/10 wt. % H₂O 0.75 mm × 3 mm 20 1285 wt. % NMP/15 wt. % H₂O 0.75 mm × 3 mm 20 14 80 wt. % NMP/20 wt. % H₂O0.75 mm × 3 mm 20 16 70 wt. % NMP/30 wt. % H₂O 0.75 mm × 3 mm 20 22 60wt. % NMP/40 wt. % H₂O 0.75 mm × 3 mm 20 32 50 wt. % NMP/50 wt. % H₂O0.75 mm × 3 mm 20 36 40 wt. % NMP/60 wt. % H₂O 0.75 mm × 3 mm 20 46 20wt. % NMP/80 wt. % H₂O 0.75 mm × 3 mm 20 51 100 wt. % H₂O 0.75 mm × 3 mm20 79

Example 23 FDCA Solubility Studies in Various Solvent Compositions

A series of samples containing various amounts of FDCA and mixed solventcompositions were prepared in sealed pressure ampules (typicallycontaining 2-5 g material (FDCA and solvent composition)). For example,200 mg FDCA, 900 mg NMP, and 900 mg de-ionized water were added to an 8mL glass vial with a stir bar inside, corresponding to a mixturecontaining 10 wt % FDCA. Other samples corresponding to different wt %FDCA samples in various mixed solvent compositions were prepared in asimilar manner. These vials were sealed and heated at a desiredtemperature for ca. 60 minutes with stirring, and samples were thenvisually inspected to determine if FDCA had totally dissolved (a clearsolution represented dissolution of the FDCA, while a cloudy solutionsuggested incomplete dissolution). The reported FDCA solubility in Table11 represents the maximum wt % FDCA that can be dissolved in the givensolvent composition using this testing method.

TABLE 11 FDCA Solubilities in Various Solvent Compositions. FDCA SolventH₂O Temperature solubility Organic solvent (wt. %) (wt. %) (° C.) (wt.%) NMP 50 50 23 2.5 NMP 50 50 100 14.5 NMP 50 50 120 19.5 NMP 35 65 230.5 NMP 35 65 100 9.0 NMP 35 65 120 13.5 NMP 20 80 23 0.3 NMP 20 80 1004.0 NMP 20 80 120 7.5 But0H 50 50 100 7.0 But0H 75 25 100 7.5 MEK 25 75100 5.5 MEK 90 10 100 4.0 gamma-valerolactone 25 75 100 4.0gamma-valerolactone 50 50 100 7.0 gamma-valerolactone 75 25 100 6.5

Example 24 FDCA Solubility in Various Dioxane/H₂O and DME/H₂O SolventCompositions at Different Temperatures

A protocol similar to that described in Example 23 was used to generatesolubility data for FDCA in various Dioxane/H₂O and DME/H₂O solventcompositions. The results for Dioxane/H₂O solvent compositions are shownin FIG. 12. The results for DME/H₂O solvent compositions are shown inFIG. 13.

Example 25 Conversion of Fructose to HMF Using HBr in NMP AnalyticalConditions

Fructose remaining was quantified by HPLC using a Rezex RCU-USP column(Ca⁺² form, 4×250 mm, 8 m) and a refractive index detector (RID).Fructose was eluted isocratically with a mobile phase of H₂O.

Isomeric forms of difructose anhydrides, collectively referred to asintermediates, were quantified by HPLC using a Thermo ScientificHypercarb column (3×50 mm, 3 μm) and a Charged Aerosol Detector (CAD).Intermediates were eluted by employing a mobile phase gradient of up to15% CH₃CN in H₂O containing 0.1% TFA. 5-Hydroxymethylfurfural (HMF) wasquantified by HPLC with UV detection at 254 nm using a Thermo ScientificHypercarb column (3×50 mm, 3 μm). HMF was eluted by employing a mobilephase gradient of up to 15% CH₃CN in H₂O containing 0.1% TFA.

Fructose and HMF were quantified by fitting to calibration curvesgenerated from pure standards. Intermediates were quantified by fittingto a calibration curve generated fromdi-D-fructofuranose-1,2′:2,3′-dianhydride (DFA-III). DFA-III waspurchased from Wako Chemicals.

Screening Conditions General Procedure A. For Reactions Carried OutUsing Microwave Heating.

Reaction stock solutions were prepared by first dissolving fructose inN-methyl-2-pyrrolidone (NMP) and H₂O. Acid catalyst was added last usingeither concentrated aqueous HBr (48 wt %) or concentrated H₂SO₄ (97 wt%). The final composition of each stock solution contained 0.6Mfructose, 0.1M acid, and 2.0M H₂O.

Reactions were carried out using a Biotage Initiator Microwave reactor.The wattage output of the reactor was varied by the instrument in orderto maintain a target temperature. Microwave vials, equipped with amagnetic stir bar, were charged with 3 g of stock solution and sealed.

General Procedure B. For Reactions Carried Out Using ConventionalHeating.

Reaction stock solutions were prepared by first dissolving fructose inN-methyl-2-pyrrolidone (NMP) and H₂O. Acid catalyst was added last usingeither concentrated aqueous HBr (48 wt %) or concentrated HCl (37 wt %).Each stock solution prepared contained 0.6M fructose. Acid and H₂Oconcentration was varied for these experiments. The concentrationstested are listed below in Tables 13 and 14.

Reactions were carried out in 8 mL glass vials using conventionalheating with magnetic stirring. Reaction vials, equipped with a magneticstir bar, were charged with 3 g of stock solution and sealed. Vials wereplaced in a pre-heated aluminum block set to the desired temperature.

Example 25.1: Comparison of HBr and H₂SO₄ as Catalyst Using GeneralProcedure A

Conditions tested along with results are listed in Table 12 and depictedgraphically in FIG. 14. These results show that a higher yield of HMFcan be achieved using HBr as catalyst compared to H₂SO₄. The yield ofHMF was not sensitive to a change in reaction temperature within therange of 120-160° C.

TABLE 12 Conditions tested and results using General Procedure A.Temper- Heating % ature Time Con- % Selec- Entry Catalyst (° C.) (min)¹version² HMF tivity³ 1 HBr 120 5 93.3 81.9 87.8 2 HBr 120 10 95.9 83.887.4 3 HBr 120 20 98.6 83.6 84.8 4 HBr 140 1 94.9 82.9 87.3 5 HBr 140 298.3 83.9 85.3 6 HBr 140 4 99.3 84.3 84.9 7 HBr 160 0.5 99.3 84.1 84.6 8HBr 160 1 99.6 84.8 85.1 9 HBr 160 2 100 83.9 83.9 10 H₂SO₄ 120 10 71.263.6 89.4 11 H₂SO₄ 120 30 85.2 74.7 87.7 12 H₂SO₄ 120 50 89.2 76.1 85.413 H₂SO₄ 140 2 79.9 70 87.6 14 H₂SO₄ 140 5 87.6 76 86.7 15 H₂SO₄ 140 1092.8 78.3 84.4 16 H₂SO₄ 160 1 88.4 77.1 87.2 17 H₂SO₄ 160 2 94.5 79.784.4 18 H₂SO₄ 160 4 97.8 81.8 83.6 ¹Does not include ramp time to targettemperature. ²% Conversion = 100 − (% Fructose + % Intermediates).³Selectivity = (% HMF/% Conversion) * 100.

Example 25.2: Comparison of HBr and HCl as Catalyst at 120° C. UsingGeneral Procedure B

Conditions tested along with results are listed in Table 13 and depictedgraphically in FIG. 15. These results show that higher HMF yield can beachieved using HBr as catalyst compared to HCl.

TABLE 13 Results of conditions tested at 120° C. using General ProcedureB. [Cat- Heating Cat- alyst] H₂O Time % Con- % Selec- Entry alyst (M)(M) (min) version¹ HMF tivity² 1 HBr 0.06 0.29 30 94.6 83.4 88.2 2 HBr0.06 0.29 30 93.3 83.1 89.1 3 HBr 0.06 0.29 60 97.8 85.0 87.0 4 HBr 0.060.29 60 97.5 85.8 88.0 5 HBr 0.06 0.29 90 98.2 85.3 86.9 6 HBr 0.06 0.2990 98.6 85.1 86.2 7 HBr 0.06 2 30 93.9 82.2 87.6 8 HBr 0.06 2 60 96.785.5 88.4 9 HBr 0.06 2 90 97.2 85.2 87.7 10 HCl 0.045 0.29 30 90.1 73.181.1 11 HCl 0.045 0.29 60 93.9 73.8 78.6 12 HCl 0.045 0.29 90 95.2 74.378.0 13 HCl 0.045 2 30 92.3 74.8 81.1 14 HCl 0.045 2 60 95.3 76.2 79.915 HCl 0.045 2 90 95.9 76.7 79.9 ¹% Conversion = 100 − (% Fructose + %Intermediates). ²Selectivity = (% HMF/% Conversion) * 100.

Example 25.3: Comparison of 100° C. and 120° C. Reaction TemperatureUsing General Procedure B

Conditions tested along with results are listed in Table 14 and depictedgraphically in FIG. 16. These results show an increase in HMF yield whenthe reaction temperature is reduced from 120° C. to 100° C.

TABLE 14 Results of conditions tested using General Procedure B. Temper-Heating [HBr] H₂O ature Time % Con- % Selec- Entry (M) (M) (° C.) (min)version¹ HMF tivity² 1 0.12 0.58 100 18 86.8 80.8 93.2 2 0.12 0.58 10027 88.1 82.6 93.7 3 0.12 0.58 100 36 90.2 84.1 93.2 4 0.12 0.58 100 5793.0 85.6 92.0 5 0.14 0.68 100 60 94.8 86.9 91.7 6 0.14 0.68 100 75 95.787.6 91.5 7 0.14 0.68 100 90 96.5 87.6 90.8 8 0.14 2 100 25 87.4 81.993.8 9 0.14 2 100 35 91.7 84.3 92.0 10 0.14 2 100 45 91.7 85.3 93.0 110.14 2 100 65 93.9 86.0 91.6 12 0.16 4 100 37 88.9 82.2 92.5 13 0.16 4100 53 91.8 84.5 92.1 14 0.2 4 100 60 93.9 86.0 91.5 15 0.16 4 100 7093.4 85.6 91.7 16 0.2 4 100 75 95.0 86.5 91.0 17 0.16 4 100 90 94.4 87.192.3 18 0.2 4 100 90 95.5 87.6 91.8 19 0.06 0.29 120 30 94.6 83.4 88.220 0.06 0.29 120 30 93.3 83.1 89.1 21 0.06 0.29 120 60 97.8 85.0 87.0 220.06 0.29 120 60 97.5 85.8 88.0 23 0.06 0.29 120 90 98.2 85.3 86.9 240.06 0.29 120 90 98.6 85.1 86.2 25 0.06 2 120 30 93.9 82.2 87.6 26 0.062 120 60 96.7 85.5 88.4 27 0.06 2 120 90 97.2 85.2 87.7 ¹% Conversion =100 − (% Fructose + % Intermediates). ²Selectivity = (% HMF/%Conversion) * 100.

While preferred embodiments of the disclosure have been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the disclosure.

1. (canceled)
 2. A process for producing a first 2,5-furandicarboxylicacid (FDCA) pathway product from a first furanic oxidation substrate,the process comprising: (a) contacting a first oxidation feedstockcomprising a first furanic oxidation substrate and a first oxidationsolvent with oxygen in the presence of a first heterogeneous oxidationcatalyst under conditions sufficient to form a reaction mixture foroxidizing the first furanic oxidation substrate to a first FDCA pathwayproduct, and producing the first FDCA pathway product; wherein the firstoxidation solvent is a multi-component solvent comprising water and awater-miscible aprotic organic solvent; wherein no base is added to thereaction mixture during (first) contacting step (a); wherein the firstoxidation feedstock has a pH of less than about 6; wherein the firstheterogeneous oxidation catalyst comprises a first solid support and afirst noble metal, and wherein the solid support comprises a specificsurface area in the range of from or any number in between 20 m²/g to100 m²/g.
 3. The process of claim 2, wherein the first noble metal isselected from the group consisting of platinum, gold, and combinationsthereof.
 4. The process of claim 2, wherein the water-miscible aproticorganic solvent is selected from the group consisting oftetrahydrofuran, a glyme, dioxane, a dioxolane, dimethylformamide,dimethylsulfoxide, sulfolane, acetone, N-methyl-2-pyrrolidone (“NMP”),methyl ethyl ketone (“MEK”), and gamma-valerolactone; and, if thewater-miscible aprotic organic solvent is a glyme, then the glyme isselected from the group consisting of a monoglyme (1,2-dimethoxyethane),ethyl glyme, diglyme (diethylene glycol dimethyl ether), ethyl diglyme,triglyme, butyl diglyme, tetraglyme, and a polyglyme.
 5. The process ofclaim 4, wherein the water-miscible aprotic organic solvent is a glyme.6. The process of claim 5, wherein the water-miscible aprotic organicsolvent is 1,2-dimethoxyethane (“DME”).
 7. The process of claim 5,wherein the water-miscible aprotic organic solvent is diglyme.
 8. Theprocess of claim 4, wherein the water-miscible aprotic organic solventis dioxane.
 9. The process of claim 4, wherein the water-miscibleaprotic organic solvent is NMP.
 10. The process of claim 4, wherein thewater-miscible aprotic organic solvent is MEK.
 11. The process of claim2, wherein the weight percent ratio of the water-miscible aproticorganic solvent:water is in the range of from or any number in between70:30 to 20:80.
 12. The process of claim 11, wherein the weight percentratio of the water-miscible aprotic organic solvent:water is in therange of from or any number in between 60:40 to 40:60.
 13. The processof claim 2, wherein the first oxidation feedstock comprises the firstfuranic oxidation substrate at a concentration of at least 5% by weight.14. The process of claim 2, wherein the first heterogeneous oxidationcatalyst comprises the first noble metal at a loading in the range offrom or any number in between 0.3% to 5% by weight of the firstheterogeneous oxidation catalyst.
 15. The process of claim 2, whereinthe first solid support comprises a material selected from the groupconsisting of a metal oxide, a carbonaceous material, a polymer, a metalsilicate, a metal carbide, and any combination of two or more thereof.16. The process of claim 2, wherein the first solid support comprises aplurality of pores.
 17. The process of claim 16, wherein the first solidsupport comprises a pore volume wherein at least 50% of the pore volumeis from pores having a pore diameter in the range of from or any numberin between 5 nm to 100 nm.
 18. The process of claim 2, wherein the firstsolid support comprises a specific surface area of about 25 m²/g. 19.The process of claim 2, wherein the first solid support comprises aspecific surface area of about 20 m²/g.
 20. The process of claim 2,wherein the first solid support comprises a specific surface area in therange of from or any number in between 20 m²/g to 30 m²/g.
 21. Theprocess of claim 2, wherein oxygen is present at a molar ratio ofoxygen:the first furanic oxidation substrate in the range of from or anynumber in between 2:1 to 10:1.
 22. The process of claim 2, wherein(first) contacting step (a) is carried out at a temperature in the rangeof from or any number in between 50° C. to 200° C.
 23. The process ofclaim 2, wherein the first FDCA pathway product is produced at a yieldof at least 80%.
 24. The process of claim 2, wherein the first FDCApathway product is FDCA.
 25. The process of claim 2, wherein the firstoxidation feedstock has a pH of about 3-6.
 26. The process of claim 2,further comprising a second oxidation step, wherein the second oxidationstep comprises: (b) contacting a second oxidation feedstock comprising asecond furanic oxidation substrate and a second oxidation solvent withoxygen in the presence of a second heterogeneous oxidation catalystunder conditions sufficient to form a second reaction mixture foroxidizing the second furanic oxidation substrate to produce a secondFDCA pathway product, and producing the second FDCA pathway product;wherein the first FDCA pathway product is an FDCA pathway intermediatecompound, either alone or together with FDCA; wherein the second furanicoxidation substrate is the first FDCA pathway product; and wherein thesecond heterogeneous oxidation catalyst comprises a second solid supportand a second noble metal, that may be the same or different from thefirst noble metal.
 27. The process of claim 26, wherein the second noblemetal is selected from the group consisting of platinum, gold, and acombination thereof.
 28. The process of claim 26, wherein the secondsolid support comprises a plurality of pores.
 29. The process of claim26, wherein the second solid support comprises a specific surface areain the range of from or any number in between 20 m²/g to 100 m²/g. 30.The process of claim 26, wherein the second solid support comprises aspecific surface area in the range of from or any number in between 20m²/g to 30 m²/g.
 31. The process of claim 2, further comprising: (a^(o))prior to (first) contacting step (a), contacting a carbohydratefeedstock comprising a sugar and a dehydration solvent with adehydration catalyst under conditions sufficient to form a dehydrationreaction mixture for dehydrating the sugar to produce the first furanicoxidation substrate, wherein the first furanic oxidation substrate ispresent in a dehydration product solution that comprises the firstfuranic oxidation substrate and the dehydration solvent.
 32. The processof claim 31, wherein the dehydration catalyst is an acid catalyst. 33.The process of claim 32, wherein the acid catalyst is an acid selectedfrom the group consisting of HBr, H₂SO₄, HNO₃, HCl, HI, H₃PO₄, triflicacid, methansulfonic acid, benzenesulfonic acid, and p-toluene sulfonicacid.
 34. The process of claim 33, wherein the acid catalyst is HCl. 35.The process of claim 31, wherein the dehydration solvent comprises1,4-dioxane and water.
 36. The process of claim 31, wherein the sugar isfructose and the first furanic oxidation substrate is HMF.
 37. Theprocess of claim 31, wherein the (prior) contacting step (a^(o)) iscarried out at a temperature between 150° C. to 180° C.
 38. The processof claim 31, wherein the (prior) contacting step (a^(o)) furthercomprises the addition of a base to the dehydration product solution.